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STANDARD SPECIFICATIONS FOR STRUCTURAL 
STEEL— TIMBER— CONCRETE AND REIN- 
FORCED CONCRETE 







Published by the 

McGraw-Hill Book- Company 

New York 

Successors to theBookDepartments of the 

McGraw Publishing Company Hill Publishing Company 

Publishers of Books for 
Electrical World The Engineering and Mining Journal 

The Engineering Record Power and The Engineer 

Electric Railway Journal American Machinist 



STANDARD SPECIFICATIONS 



FOR 



S TRUCTURAL S 7 'EEL-TIMBER-CON CRETE 
AND REINFORCED CONCRETE 



BY 

■ 

JOHN C. OSTRUP, C.E. 

I I 
CONSULTING ENGINEER 

Professor of Structural Engineering, Stevens Institute of Technology; Member American 

Society of Civil Engineers; Member Institution of Civil Engineers; 

Member American Society Promotion Engineering Education; 

Member American Society Advancement of Science, 

etc., etc. 



McGRAW-HILL HOOK COMPANY 
239 WEST 39TH STREET, NEW YORK 
6 Bouverib Street, London, E.C. 
1910 






X 



right, 1910, by 
AW-HILL BOOK COMPANY 



5140 



PREFACE 



A serious attempt has been made to incorporate into one 
volume a set of ten specifications, which not only cover the 
most important materials used in construction work of any 
magnitude, but which are condensed so as to avoid unnecessary 
repetitions, are consistent throughout, and which, at the same 
time, conform in every essential to the latest experiments and 
investigations, to the best authorities, to modern practice, and 
to the author's own considerable experience. 

Of new matter, particular attention is called to the specifica- 
tions for reinforced concrete, as these are rather extensive, 
probably the first complete set m existence. 

To facilitate the use of all specifications, the subject matter 
in each has been arranged, as nearly as possible, in the order, 
or rotation, in which the information is wanted. 

Any designs made, or structures built in strict accordance 
with these specifications will insure first-class details, excellent 
materials, and creditable workmanship, as well as safety, dura- 
bility, and economy. Hence they are designed to be equally 
well suited to the needs of engineers, architects, contractors, 
college professors and their students. 

In the body of the specifications credit has been accorded to 

authorities, when quoted, to whom thanks are due. Thanks 

are also due to Francis P. Wittmcr, M. Am. Soc. C.E., and others 

for many valuable suggestions. J. C. 0. 

New York, September, 1910. 

V 



CONTENTS 



TART PAGE 

I. Steel Framework of Buildings 1 

II. Highway Bridges # 13 

III. Railroad Bridges 26 

IV. Plate Girders 37 

V. Materials and Workmanship 43 

VI. Inspection, Painting and Erection 54 

VII. Structural Timber 58 

VIII. Cement 65 

IX. Portland-Cement Concrete. . . 70 

X. Reinforced Concrete 75 

vii 



STANDARD SPECIFICATIONS FOR STRUC- 
TURAL STEEL-TIMBER-CONCRETE AND 
REINFORCED CONCRETE 



PART 1 

STEEL FRAMEWORK OF BUILDINGS 

Dead, Snow, and Wind Loads 

i. The Dead Load upon any part of a structure shall con- 
sist of the calculated weight of the materials and fixtures carried 
permanently by such part. 

2. The actual weight of the different materials shall be 
computed as accurately as possible and, if necessary, a trial 
design shall be made to ascertain the weight of any portion in 
doubt. 

3. Roof Covering. The weight of roof covering will average, 
for each square foot of superficial roof area, as follows: 

Corrugated steel 2-3 lbs. 

Shingles 1 6 

Roofing files 6-8 

Slate (J to i" thick) 6-8 

Gravel and composition s LO 

Terra-cotta, 2" thick (flat arch) 10 15 

Concrete, per inch thickness (Hat arch).. LO 12 

Plank sheathing, per inch thickness 3 I 



2 STANDARD SPECIFICATIONS 

4. Purlins. The weight of purlins will average, for each 
square foot of superficial roof area, as follows: 

Steel purlins 2-3 lbs. 

Wooden purlins 3-5 " 

5. Roof Trusses. The weight of ordinary steel roof trusses, 
having a pitch of -^ to J, will average, for each square foot of 
horizontal area, as follows: 



or for the total weight of one truss, 

Tr=<§(L + io), 

where lT=total weight of truss in lbs. 

c=weight in lbs. per sq.ft. on horizontal area carried by 

truss. 

d=distance in feet between trusses, provided that c/> — 

5 

(Par. 23). 

L = span in feet of truss. 

6. Snow Load. In latitudes between 40° and 50° the snow 
load shall be taken per horizontal square foot of roof area as 
follows : 

Pitch from flat to ^ inclusive 25 lbs. 

" over i to i " 20 " 

" i to i " 15 " 

" i to i " 10 " 

" i and" more " 

In other latitudes these snow loads should be modified according 
to local conditions. 

7. Wind Pressure. The wind pressure shall be taken as 
30 lbs. per sq.ft., upon the entire exposed area of the steel 
framework, or upon the vertical projection of sides and ends of 
roof and building, and as acting horizontally in any direction. 



STEEL FRAMEWORK OF BUILDINGS 3 

8. Minimum Roof Load. The minimum roof load, which 
will include the dead, snow, and wind loads, shall be taken as 
follows : 

On roof covering and purlins, 40 lbs. per sq.ft. 

of superficial area. 
On roof trusses, 40 lbs. per sq.ft. of horizontal area. 

Live Loads 

g. Live Loads on Floors. 

(a) The live loads on floors shall be considered as being uni- 
form over their entire area and shall be taken, as a minimum, 
per square foot as follows: 



Dwellings, apartment houses, hotels, 

hospitals 50 lbs. and up 

Office buildings 60 " 

Schools, theaters, churches 75 

Ordinary stores, public buildings . . . 100 

Warehouses, factories, armories 200 

When designing flooring, joists, girders, etc., the probability of 
concentrated loads, such as pianos, safes, machinery, wagons, 
etc., must be considered and provided for. 

(6) The above live loads, except in warehouses and other 
buildings exposed to simultaneous loading on all floors, may 
be reduced for columns as follows: 

Columns supporting roof and top floor, no reduction. 

" next ten floors, a cumulative reduction 
of 5 per cent for each succeeding 
floor. 
" " remaining floors, a total reduction 

of 50 per cent. 

io. Crane Loads. The actual weighl of the crane, its dimen- 
sions and its lifting capacity shall l>r used if obtainable, other- 
wise the following data for Typical Electrical Traveling Cranes* 

shall be used: 

* Mr. C. C. Schneider in Trans. Am. Soc. C. E., Vol. 54. 



STANDARD SPECIFICATIONS 



Capacity 



Wheel 
Base. 



Ft. In. 



Maximum 

Wheel 

Load in 

Pounds. 



Weight of Rail 
per Yard for 



Plate 
Girders. 
Pounds. 



Beams. 
Pounds. 



5 Tons 


40 
-60 


8 6 

9 


12.000 
13.000 


10 
10 


_ 


40 
40 


40 
40 


10 •• 


40 


9 


19,000 


10 


- 


45 


40 


.60 


9 6 


21,000 


10 


- 


45 


40 


15 • 


40 




26.000 


10 


7 


50 


50 




10 


20.000 


10 


7 


50 


50 


20 •* 


40 


10 


33.000 


12 


- 


55 


50 


10 6 


36.000 


12 


S 


55 


50 


9*1 


40 


10 


40.000 


12 


- 


60 


50 


-O 


' 60 


10 6 


44.000 


12 


8 


60 


50 


30 '• 


40 


10 6 


48,000 


12 


8 


70 


60 


' 60 


11 


52,000 


12 


8 


70 


60 


40 •• 


'40 


11 


64.000 


14 


9 


80 


60 


' 60 


12 


70.000 


14 


9 


80 


60 


50 - 


40 


11 


72.0(H) 


14 


9 


100 


60 




12 


SO. 000 


14 


9 


100 


60 



where •> = Side clearance from center of rail. 
v= Vertical clearance from top of rail. 

(a) A wheel-load shall be assumed as distributed in the top 
flange, over a distance equal to depth of girder, with 
a maximum of 30 inches. 
In addition to the vertical load, the top flanges of the 
girder shall withstand a lateral loading of two-tenths 
(j-j) of the lifting capacity of the crane, equally 
divided between the four wheels of the crane. 
ii. Impact Loads. For beams, girders, and columns carry- 
ing traveling cranes an allowance of 25 per cent of the computed 
moments and shears due to same shall be added to compensate 
for the effects of impact and vibration. 



Unit Stresses : Steelwork • 

12. In designing the component parts of any building the 
maximum stresses due to the combined effects of axial stresses 
and bending stresses from dead, snow, wind and live loads, includ- 
ing impact, if any. shall not exceed, for structural steel and rivet 
steel, the following values in lbs. per square inch, except as modi- 
fied in Pars. 14-16. 



STEEL FRAMEWORK OF BUILDINGS 5 

(a) Axial tension in main members, net section 16,000 lbs. 

in wind bracing, " 20,000 " 

(b) Bending, net section, on extreme fibers of: 

Rolled shapes, built sections and 

plate girders 16,000 lbs. 

Pins 20,000 " 

(c) Axial compression in main members, gross section, 

£=16,000-70-, 
r 

where *S=allowable unit stress. 

/ = unsupported length of member in inches. 

r = least radius of gyration of member in inches. (Per. 39.) 

(d) Shear on: Turned bolts, and field rivets 

when hand driven 7,500 lbs. 

Field rivets when power driven. 9,000 " 

Shop rivets and pins 10,000 " 

Plate girder webs, gross section. 10,000 " 

(e) Bearing on: Turned bolts and field rivets 

when hand driven 15,000 " 

Field rivets when power driven . 1 8 ,000 ' ' 

Shop rivets and pins . 20,000 " 

13. Expansion Rollers. 

Allowable pressure per lin. in 600d 

where d= diameter of roller in inches. 

14. Combined Stresses. When the effect of bending stresses 
due to wind loading is considered and added to the axial and 
bending stresses, due to other causes, the above unit stresses 
(Par. 12) may be increased 25 per cent. 

15. Eccentric Stresses. Provision must be made for eccen- 
tric loading on columns and other members. Whenever angles 
used as web members or bracing are connected up by one leg- 
only, the above unit stresses (Par. L2) shall be decreased 25 per 
cent. 

16. Reversal of Stresses. Members and connections sub- 
ject to reversal of stresses shall be proportioned for an equivalenl 
.stress equal to thai stress which, when added bo 50 per cent of 
the other, will give the greater section. 



6 STANDARD SPECIFICATIONS 

17. Cast Iron. The maximum stresses shall not exceed, 
in pounds per square inch, for 

Tension _ 2.500 lbs. 

Compression (on blocks) 'l2,000 " 

Shear 1,500 " 

Unit Stresses: Masonry, Foundations 

18. Pressure on Walls. The pressure on walls caused by 
beams, girders, wall plates, etc., shall not exceed the following 
values in pounds per square inch. 

On brickwork, laid in lime mortar. . . . 150 lbs. 

cement mortar. 200 " 

On terra-cotta, hollow 75 " 

solid 150 " 

On cinder concrete 1:2:6 125 " 

On Portland cement concrete 1:2^:5. 275 " 

1:2 :4. 350 ". 
On ordinary rubble masonry, cement 

mortar 150 " 

On first -class stone masonry, cement 

mortar 400-600 " . 

19. Pressure on Foundations. The pressure on masonry 
or foundations caused by column bases, etc.. shall not exceed 
the following values in pounds per square inch: 

Dimension stones 125 lbs. 

Portland cement concrete 1 :2| :o 300 " 

1:2 :4 400 " 

1:2:0 (grani- 
toid) . . 600 " 
Other values as given above (Pars. 17. IS). 

20. Pressure on Soils. The pressure on soils caused by 
foundations, walls, etc.. shall not exceed the following values in 
tons per square foot: 



STEEL FRAMEWORK OF BUILDINGS 7. 

Earth, ordinary lh tons 

" tamped or naturally solid 3 " 

Clay, soft " 1 " 

" dry or mixed with dry sand 2 " 

" hard pan 3 " 

" hard and mixed with coarse sand. . . 4 " 

Sand and gravel mixed, when dry and 

coarse 6 " 

Rock, broken or partly disintegrated 5-25 " 

Rock, solid bed 200 " 

21. Bearing Power of Piles. Wooden piles shall be spaced 
not less than 30 in. c. to c. 

When the piles are driven through wet and loose soil to a 
good bearing the pressure shall not exceed 300 lbs. per sq. in. 
of their average cross-section. When driven through a firm soil 
this pressure may be increased to 600 lbs. (Pars. 270, 277.) 

Design of Framing 

22. Roof Trusses. Roof trusses shall preferably be of such 
type as will allow the purlins to be placed only at the panel 
points. Wherever this is neither practicable nor economical, 
the top chord shall be designed for both bending and direct 
stresses. 

Roof trusses shall be riveted throughout, except in special 
cases for long spans where the field splices and main joints may 
be pin-connected. 

23. Spacing of Roof Trusses. The spacing of roof trusses 
shall preferably be such as to allow only the use of single rolled 
shapes as purlins (Par. 26). Whenever this limit be exceeded 
intermediate jack-rafters may be used. For ordinary roofs the 
most economical spacing of trusses will generally be as follows: 



tor 


spans up to 


40 ft. 


16' 


0" c. 


to ( 


u 


" from 


K) 55 ■• 


17' 


0" 


" 


it 


a a 


55 70 " 


IS' 


0" 


it 


it 


a a 


70 85 " 


\\v 


0" 


n 


a 


a 


85 LOO" 


20' 


0" 





8 STANDARD SPECIFICATIONS 

24. Pitch of Roofs. The pitch must vary according to cir- 
cumstances, but shall preferably be made as follows: 

For tar and gravel roofs from ^ to J-j- 

" tile, corrugated steel and 

shingled roofs " i to J 

" slate roofs " J and up 

25. Bracing. Roof trusses shall be braced in pairs; in the 
plane of the top chord the bracing may be made adjust able , 
whereas in the plane of the bottom chord the bracing must be 
rigid. 

Bracing in planes of the sides and ends of buildings may also 
be made adjustable. 

Knee-braces must be provided wherever practicable, for 
instance, between trusses and columns and between crane 
girders and columns. 

26. Purlins. Both steel and timber purlins shall be attached 
to the roof trusses by means of lug angles. Steel purlins shall 
be composed of single-rolled shapes (Z-bars, Cs, I-beams and Ls) 
whenever possible, and be of a depth 5: than one-thirtieth (3^) 
of the span. Otherwise plate girder or lattice girder purlins 
shall be used, and no trussed purlins will be permitted. 

Purlins shall generally be spaced from 4 ft. to 5 ft. apart for 
all forms of roof covering except reinforced concrete, where the 
spacing may be increased to 12 ft. 

27. Girts. Girts shall be attached to columns by means of lug 
angles and shall be composed of single rolled shapes. They shall 
generally not be spaced more than 4 ft. apart. 

28. Beam Girders. Beams composed of single rolled shapes 
(I-beams and r» shall be proportioned by their moment of 
inertia. 

Xo beam shall be used whose flange width is less than one- 
twentieth ( t l) of the span length, unless its compression flange 
is properly supported side wise against buckling. AVhen more 
than one beam is used to form a girder, they shall be connected 
by bolts and separators, so as to bring the unsupported flange 
width within the above ratio, spaced with a maximum limit of 
5 ft. Beams used in floors shall have a depth of not less than 
one-twentieth Q^) of the span length; they shall be riveted 



STEEL FRAMEWORK OF BUILDINGS 9 

to the columns, whenever such occur, by means of connection 
angles which must carry the entire load. Shelf angles may be 
provided for convenience during the erection. The free end 
of such floor beams must be securely anchored to the walls. 

29. Plate Girders (see Part IV). 

Details of Design 

30. Minimum Size of Material. No rolled shape or metal 
of less thickness than \ in. shall be used except for fillers. No 
angles shall be less than 2%"X2 ,, Xi" and no rivets, except in 
beam connections and lacing bars, shall be less than f in. in 
diam. (Pars. 33, 38, 45, 46.) 

31. Details of Joints. Main members of trusses shall be so 
arranged around the joints that their neutral axes will meet 
in a common point. 

All joints in riveted work, whether in tension or in compres- 
sion, shall be fully spliced. 

32. Details of Connections. The strength of connections shall 
be such as to cause the main member to fail should the combina- 
tion be tested to destruction. No connection, except for lattice 
bars, shall have less than two rivets. 

33. Rivets. In main members composed of angles the maxi- 
mum diameter of rivet used shall not exceed one-quarter (J-) 
the width of leg through which it passes. Three-quarter (f) 
in. rivets shall not be countersunk in plates less than f in. in 
thickness and J-in. rivets shall not be countersunk in plates, 
less than ^ in. in thickness. 

Except in bed plates, no rivet shall be of loss diameter than 
the thickness of the thickest plate through which it passes. 

34. Rivet Spacing. The minimum pitch shall never be less 
than three diameters of the rivet and, if possible, not less than 
3" for J" rivets, 2£" for \" rivets, 2J" for |" rivets, and If" lor 
\" rivets. 

The maximum pitch of rivets, in the direction of the stress, 
shall not exceed 6 in., or 1(> times the thinnest outside plate con- 
nected, and not more than 10 times that thickness at right angles 
to the stress, except when two or more plates in contact are to 
be held together, where the pitch may be L2 in. in any direction. 

The maximum pitch at ends of built up compression mem- 



10 STANDARD SPECIFICATIONS 

bers shall not exceed four diameters of the rivet for a length 
equal to two times the width of the member. 

35. Edge Distance of Rivets. The minimum distance from 
the center of any rivet hole to a sheared edge shall be H" for 
i" rivets. 1J" for f" rivets, \\" for f" rivets, and 1" for \" rivets, 
and to a rolled edge, except in flanges of I-beams and channels, 
1}". 1J", 1" and \" respectively. The maximum distance from 
an}- edge shall be eight (8) times the thickness of the outside 
plate, but shall not exceed 5*in. 

36. Tension Members. In calculating the net area of tension 
members the area of rivet holes must be deducted, assuming 
the diameter of the hole \ in. larger than the nominal size of 
the rivet. 

Main tension members shall be composed of sections placed 
symmetrically about the central plane through the truss. Second- 
ary tension members may be made of a single shape. (Par. 15.) 

Pin-connected riveted tension members shall have a net 
section through the pin hole 25 per cent in excess of that through 
the body of the main member. The minimum net section back 
of the pin hole, parallel to the axis of the member, shall not be 
less than that through the body of the main member. 

37. Eye-bars. Heads of eye-bars shall be forged and so 
proportioned as to develop the full strength of the bar. (Par. 

43.) 

The eye-bars shall be placed in the truss so as to be, as nearly 
as possible, parallel to its central plane, the maximum incli- 
nation being limited to 1 in. in 16 ft. 

38. Rods. The minimum size of bracing rods, or laterals, 
shall be f in. in diameter and they shall be upset at the screw ends. 
The minimum size of sag rods shall be f in. in diameter, but these 
need not be upset. 

39. Compression Members. Main compression members shall 
be composed of sections placed symmetrically about the central 
plane through the truss. Sub-struts may be made of a single 
shape. (Par. 15.) 

Xo compression member shall have a length exceeding 120 
times its least radius of gyration, except those used for wind and 
lateral bracing, which ma}- have a maximum length of 140 times 
their least radius of gyration. 

40. Tie-Plates. The open sides of compression members 



STEEL FRAMEWORK OF BUILDINGS 11 

shall be stayed by diagonal lattice having tie-plates as near each 
end as practicable and at intermediate points where the lattice 
is interrupted. In the main members the tie-plates shall have 
a length of not less than the width of the main member on the 
connected side, provided that no tie-plate be less than 10 in. long 
near the ends of such members. 

Their minimum thickness shall be one-forty-eighth (Jg) f the 
distance between center lines of the connecting rivets. 

41. Columns. In proportioning the area of columns the 
effect of bending stresses due to wind or eccentric loading shall 
be included. 

Columns shall have as few splices as practicable and, whore 
spliced, the splices shall be strong enough to resist the direct 
as well as the bending stresses. 

42. Lattice Bars. Single lattice bars shall have an inclination 
of approximately 60° with the axis of the main member and shall 
have a minimum thickness of one-fortieth (-j-^) of the distance 
between the rivets connecting them to the member. 

Single lattice bars may be connected with one rivet, except 
in flanges more than 5 in. wide, where two rivets shall be 
used. Lattice angles shall be connected by at least two rivets. 

Double lattice bars shall be used where the distance between 
rivet lines in the flanges exceeds 15 in. They shall have a mini- 
mum thickness of one-sixtieth (-^ ) of the distance between the 
rivets connecting them to the member, shall have an inclination 
of approximately 45°, and shall be riveted at their intersection. 

The minimum width of lattice bars shall be: 



lor 15-in. channels, or built sections with 1 _, . 

. _ . ' 2\ in. ( fr-m. rivets) 

angles over 3 in J " 

For 12-, 10-, and 9-in. channels, or built sec- 1 rt1 . . . , N 

..,.,. , - in. (i-in. rivets) 

tions with ->-m. angles 1 

For 8- and 7-in. channels, or built sections 1 . . . . . 
. 2 -in. (f-in. rivets) 

with 2\-m. angles j 

For (j-in. channels or less I , : in. I'-in. rivets) 

43. Pins. The minimum diameter of pins shall be eight- 
tenths (, s ) of the width of the widest eye-bar attached to it. 

Members shall be packed on pins, using filling rings where 
necessary, in a manner that will prevent any lateral movement. 



12 STANDARD SPECIFICATIONS 

44. Pin Holes. Pin holes shall be reinforced by plates where 
necessary. The plates shall be of such size as to distribute 
properly, through sufficient rivets, the pin pressure to the webs 
and their flanges in each segment of the main member. 

45. Wall Plates and Column Bases. The minimum thick- 
— -hall be \ in. for wall plates and § in. for base plates. The 

wall plates and column bases shall be detailed and placed in such 
a manner that the load will be evenly distributed, using cement 
mortar or grout for filling if necessary. 

They shall be of sufficient size and thickness so as not to 
exceed the allowable unit stresses. Pars. 12. 14. 17. 18 and 19.) 

46. Anchor Bolts. Columns shall be anchored to the foun- 
dations, by means of anchor bolts, when stressed in tension at 
their base. The minimum diameter of anchor bolts shall be 
t in. upset: they shall be of sufficient length to engage a mass 
of masonry, the weight of which shall be lh times the tension. 

The anchor bolts shall in all cases be of sufficient size to 
resist in shear any horizontal force acting thereon. 

47. Temperature. Where necessary provision shall be made 
for expansion and contraction covering a range of 150 c F 

48. Expansion Rollers. The minimum diameter of expan- 
sion rollers shall be 4 in. 



PART II 

HIGHWAY BRIDGES 

General Requirements 

49. Classification. Highway bridges may, based upon traffic 
conditions, be divided into three classes, viz.: 

Class A — City bridges, subject to heavy traffic. 

Class B — City, Interurban or Country bridges, subject 

to medium traffic, and 
Class C — Country bridges, subject to light traffic. 

50. Type of Bridge. The following types of bridges shall 
preferably be used: 

For spans up to 20 ft., wooden beams or rolled beams. 

" " from 20 to 40 ft., rolled beams or plate girders. 
" " " 40 to 70 ft., plate girders. 
" " " SO to 100 ft., plate girders or riveted t russes. 
" " " 100 to 160 ft., riveted trusses. 
" long spans, 160 ft. and over, pin-connected trusses. 

Pony trusses shall be avoided wherever possible, but may 
be used for spans from 40 to 90 ft. (Par. 80.) 

51. Materials. All parts of the superstructure, except the 
flooring and paving, shall be of structural steel, or rivet steel. 

Cast iron may be used for minor parts and for ornamental 
purposes; all other castings shall be of steel. 

52. Clearances. All through bridges carrying electric cars 
shall have a clear head-room, above the top of the rail, of at 
least 15 ft., for a width of 6 ft. over the center of the track. 
Where the track is straighl there shall be clear width of at least 

7 ft. on each side of the center of the track at a heighl of 12 in. 

above the top of rails. Where the tracks are curved, the addi- 

13 



14 STANDARD SPECIFICATIONS 

tional clearance shall be computed by assuming the extreme 
length of car as 45 ft., width 8 ft., and distance between centers 
of trucks 20 ft. 

Through bridges, not carrying electric cars, shall have a 
minimum head-room of 14 ft. above roadway, for classes A and 
B, and of 12 ft. 6 in. for class C, unless otherwise required by 
local ordinances. 

53. Paved Floors. Pavements consisting of stone blocks, 
paving bricks, asphalt, etc.. resting upon a bed of concrete, not 
reinforced, shall be supported upon buckled or corrugated plates. 
The minimum thickness of this concrete bed shall be 3 in. for 
the roadway and 2 in. for the sidewalks. Such floors shall be 
pitched transversely and proper provisions for their thorough 
drainage shall be made. 

Pavements consisting of wooden blocks may rest on a timber 
floor, consisting of planks laid transversely and at least 4 in. 
thick. 

54. Wooden Floors. (See Pars. 271, 279 to 281.) 

55. Cross-Ties. (See Par. 283.) 

56. Guard-Rails. (See Par. 284.) 

57. Handrailing. A handrailing 3 ft. 6 in. high shall be 
placed on each side of the bridge, except where plate girders 
serve the same purpose. Where the handrailing is of rolled 
steel or cast iron it shall be of pleasing design and shall be rigidly 
attached to the superstructure. For wooden handrailing see 
Par. 282. 

58. Approaches. All floor-timbers, rails, guards and hand- 
railings shall extend over all piers and abutments and shall make 
suitable connection with the embankments at either end of the 
structure. 

Loads 

59. Dead Load. The dead load consists of: 

(a) The weight of the steelwork: 

(b) The weight of the paving, if any; 

(c) The weight of the wooden flooring, if any. and 

(d) The weight of the electric railway tracks, if any. 

The approximate weight of the steelwork shall be obtained 
either by trial design or otherwise. 

The weight of the paving shall be taken at 160 lbs. per cu. 



HIGHWAY BRIDGES 15 

ft. for stone blocks, at 150 lbs. per cu. ft. for paving bricks, and 
at 130 lbs. per cu. ft. for concrete and asphalt. 

The weight of the wooden flooring shall be taken at 4J lbs. 
per foot-board measure for oak, yellow pine and other hard 
woods, at 3-J- lbs. per foot-board measure for white pine and 
other soft woods. 

The minimum weight of cross-ties and guard rails shall be 
taken at 200 lbs. per lin.ft. of each track, and the weight of rails, 
fastenings and splices at 100 lbs. per lin.ft. of each track. 

6o. Live Loads. All bridges shall be designed to carry cer- 
tain concentrated and certain uniformly distributed loads, as 
specified below, placed so as to give the greatest stress in each 
part of the structure. 

(a) Class A. For the floor system and local truss mem- 
bers a concentrated load of 40,000 lbs., distributed on two 
axles 8 ft. centers and 5 ft. gauge (occupying a length 
of 20 ft. and a width of 10 ft.), and upon the remaining 
area of the floor, including sidewalks, a load of 100 
lbs. per sq.ft. 

For the trusses or girders, 100 lbs. per sq.ft. of entire 1 
roadway and sidewalks for spans of 100 ft. or less, 80 
lbs. for spans of 200 ft. or over, and proportionally for 
intermediate spans. 
(6) Class B, For the floor system and local truss members 
a concentrated load of 30,000 lbs., distributed on two 
axles 8 ft. centers and 5 ft. gauge (occupying a length 
of 20 ft. and a width of 10 ft.), and upon the remaining 
area of the floor, including sidewalks, a load of 90 
11 >s. per sq.ft. 

For the trusses or girders, 00 lbs. per sq.ft. of entire 
roadway and sidewalks for spans of 100 ft. or less, 70 
lbs. for spans of 200 ft. or over and proportionally for 
intermediate spans. 
(c) Class C. For the floor system and local truss members 
a concentrated load of 20,000 lbs., distributed on two 
axles 8 ft. centers and 5 ft. gauge (occupying a length 
of 20 ft. and a width of 10 ft.), and upon the remaining 
area of the floor, including sidewalks, a load of 80 lbs. 
per sq.ft. 

For the (russes or girders, 80 lbs per sq.ft. of entire 



16 STANDARD >PE< IFICAT: - 

roadway and sidewalks for spans of 100 ft. or less 
lbs of 200 ft. or over, and proportionally 

for intermediate spans. 
(d) Electric Railways. Any bridge carrying electric railway 
epting those for exclusive railroad use» shall 
in addition to one of the above loadings be designed to 
:ry on each track a series of cars, each weighing 
100.000 lbs., unless otherwise specified. This load to be 
distributed equally on two trucks 20 ft. centers, each 
having two axles 5 ft. centers and 5 ft. gauge (occupy- 
ing a length of 40 ft. and a width of 10 " 

6i. Impact. An impact allowance shall t the 

computed maximum five load stress - - follows: 

Tor bridges of all classes earning hiehwav l _ 

traffic only .."... P^^U+I 

For bridges, or part of bridges, carrying T _ ...■ 200 \ 

electric railway traffic J ' 1—300/' 

where 5 = computed maximum five load stress, moment or shear; 
L = loaded length of span in feet. 

N •:- impact allowance shall be added to sti ss s produce 
wind, centrifugal or traction force - 

62. Wind Pressure. The wind bracing shall be designed to 
one of the following lateral loadings, whichever produces 
the greater stress: 

(a) Structure unloaded. 50 lbs. per sq.ft. on the exp - 
surface of all trusses and the floor as seen in eleva- 
tion, or 

(6) Structure loaded. (Bridges of all classes carrying high 

traffic only), 30 lbs. per sq.ft. on the exposed surface 
of all trusses and the floor as seen in' elevation in addi- 
tion to a uniform load of 150 lbs. per lin.ft. of structure 
applied on the " loaded " chord, or 

(c) Structure loaded. (Bridges of all classes earning electric 
railway traffic the same loading as under xcept 

that the additional uniform lead is 300 lbs. per lin.ft. 
of structure and is applied 7 ft. above the base of rail. 



HIGHWAY BRIDGES 17 

The minimum value of the above pressures shall be 250 lbs. 
per lin.ft. for the " loaded 77 and 150 lbs. for the " unloaded ;; 
chord of the structure. 

Trestles shall in addition to one of the above wind loadings 
be designed to resist a pressure of 200 lbs. for each vertical foot 
of bent in height. 

The above wind pressure shall in all cases be treated as 
moving loads. (Par. 61.) 

63. Centrifugal Force. Any structure on a curve carrying 
an electric railway shall be designed to resist a lateral force of 
10 per cent of the equivalent live load per lin.ft., applied 5 ft. 
above the top of rail. (Par. 61). 

64. Traction Force. Any structure carrying an electric 
railway shall be designed to resist a longitudinal force of 20 
per cent of the greatest live load placed upon the same. 



Unit Stresses 

65. Structural Steel. In designing the component parts of 
any highway structure the maximum stresses due to the com- 
bined effects from dead and live loads, including impact, or due 
to wind pressure, centrifugal and traction forces, shall not exceed 
for structural steel and rivet steel, the following values in lbs. 
per square inch, except as modified in Pars. 71 to 74. 

(a) Axial tension, net section 16. 000 lbs. 

(6) Bending, net section, on extreme fibers of rolled 

shapes (Par. 77), built sections and plate girders 16,000 
Joists, under concentrated loads, when flooring 

is non-continuous (Par. 77) 20,000 

Pins, on extreme fibers 24,000 

(c) Axial compression, gross section, 



S= 16,000 70 
r 



where S allowable unit stress. 

1 = unsupported length of member in indie-. 

r=least radius of gyration of member in inches (Pai 1)6 






18 STANDARD SPE IIFICATK - 

: turned bolts and field rivets, when 

hand driven 1,000 lbs. 

Field rivets, when power driven 11,00 

Shop driven rivets and pins 12,01 

Plate girder web- _ — section 10,01 

B i rne bolts and field .rivets, when 

rid driven : 18,000 " 

Field rivets, when power driven 22 

p-driven rivets and pins 24,00 

66. Pressure on Foundations. The pressure on masonry 
foundations shall not exceed the following values in pounds per 

i e inch : 

.and cement concrete 1:2:4 and first-class sandstone 

limestone masonry, including impact 400 lbs. 

tland cement concrete 1:2:0 (granitoid) and first-cli ss 
a anite masonry, including impact 600 ' ' 

67. Pressure on Soils. For allowable pressures see Par. 2<~>. 

68. Timber. For allowal le stresses see Part VII. 

69. Expansion Rollers. 

Allowable pressure per lin.in 

where d = diameter of roller in inches. 

70. Cast Steel. The maximum stresses shall not exceed, in. 

: 

Tension 16.000 lbs. 

ssi :. on blocks 16,000 '" 

Shear 1 

71. Combined Stresses. .111 members in a structure exp -- 
to bending stresses from a transverse loading, due either to the 
weight of the member itself, or to the weight of the floor system 
when it rests directly on one of the chords, shall be designed for 
the maximum combination of such stresses, with the axial stres - 3 
including impact I h kind of loading, using an extreme 
fiber stress = - ..in. 

Where the bending stresses are due only to the weight of the 



HIGHWAY BRIDGES 19 

member itself and do not exceed 1600 lbs. per sq.in., the effect 
may be neglected, otherwise the maximum unit stresses (Pars. 
65 and 73) may be increased 10 per cent. 

The bending moment in chord segments of riveted structures, 
or in pin-connected members when continuous over joints, shall 
be computed from the compromise formula, 

M=±1.2 wL' 2 , 

where M = positive moment at center or negative moment at 
the joint, 
w = total transverse load in lbs. per.lin. ft., 
L = length of member in feet. 

72. Eccentric Stresses. Whenever angles, used as web 
members or bracing, are connected up by one leg only the above 
unit stresses (Par. 65) shall be decreased 25 per cent. 

73. Maximum Stresses. When combining the stresses due 
to vertical forces with those due to lateral forces, including the 
direct and indirect wind stresses, centrifugal forces, and bend- 
ing stresses in the end posts due to wind, the specified unit stresses 
(Pars. 65 and 71) may be increased 25 per cent, provided that 
this combination gives a greater sectional area. 

74. Reversal of Stresses. Where the stresses due to wind 
and centrifugal forces reverse the stresses in a member due to 
vertical forces proper provisions must be made for the piece to 
resist compression. 

Members and connections subject to reversal of stresses 
shall be proportioned for an equivalent stress equal to that stress 
which, when added to 50 per cent of the other, will give the 
greater section, both impacts included. 

Design of Structi re 

75. General Dimensions. The following dimensions shall 
first be calculated or assumed: 

Span of girders, center to center of bearings. 
Span of trusses, center to center of pedestals or end pins. 
Span of floor-beams, center to center of girders or trusses. 
Span of joists or stringers, center to center of floor beams 
or one panel length. 






20 



STA X I )A R I ) SPEC JIFICATIONS 



Depth of girders, center to center of gravity of chords. 
Depth of trusses, center to center of gravity, or center to 
center of pins, of chords. 

76. General Proportions. The width between centers of 
trusses carrying a single straight electric railway track shall 
not be less than 15 ft., or for any bridge less than one-twentieth 
( ,, 1 „ ) of the span. 

The depth of plate-girder spans shall preferably not be less 
than one-twelfth (rfa) of the span, the depth of lattice girders 
and pony trusses shall not be less than one-tenth CjL) of the span, 
and the depth of riveted and pin connected through trusses shall 
preferably not be less than one-eighth (-J-) of the span, or less than 
the panel length. 

77. Floor Framing. Steel joists and stringers shall pref- 
erably be riveted to the web of the floor beams. Rolled beams 
used as joists shall be spaced not to exceed 3 ft. center to center 
and shall not have a depth of less than one-twentieth (^) of 
the span. 

If the floor plank be continuous each joist may be assumed 
to carry only two-thirds (f) of the concentrated load. The 
top flanges of stringers must be provided with securely bolted 
wooden shims for the purpose of spiking the planking thereto. 

When end floor beams are not used over the masonry the 
joists shall have their ends rigidly connected by means of struts 
and the stringers by means of cross frames. 

Floor beams shall preferably be arranged so as to be per- 
pendicular to the girder or truss at the panel points; they may 
rest upon the top chord in deck bridges, but in through bridges 
they shall be riveted to the verticals. 

Rolled beams used as joints, stringers, or floor beams shall be 
proportioned by their moment of inertia. 

78. Plate Girders. For plate girders used as stringers, floor 
beams, and main girders, see Part IV. 

79. Beam Bridges. When bridges carrying electric rail- 
ways are built of rolled beams they shall be braced as follows: 
With a single beam under each rail and for spans under 20 ft. 
the bracing shall consist of cross channels framed at each end at 
intervals not exceeding 5 ft., for spans over 20 ft. a cross channel 
framed at each end with an intermediate diagonal bracing. When 
two or more beams are placed under each rail the beams shall 



HIGHWAY BRIDGES 21 

be provided with riveted or cast-iron separators spaced not 
over 5 ft. 

80. Pony Bridges. The top chord of pony trusses shall be 
securely stayed at each panel point by means of gusset plates, 
knee braces, or wide web members of angles with lattice or web 
plate when efficiently connected to the floor beams. 

81. Deck Bridges. Trusses in deck bridges shall be pro- 
vided at each panel point in the bottom chord with vertical 
sway bracing sufficiently strong to carry the lateral forces to 
which they are subjected. 

82. Through Bridges. All trusses shall be so designed that 
the stresses may be determined with reasonable accuracy; they 
shall have stiff hip verticals, and in the bottom chord the two 
end segments shall also be made rigid whenever the stresses 
reverse or are near that point. 

All web members, including counters, except for long spans 
(Pars. 50, 94, 95), shall be made rigid. 

83. Bracing. Ends of all through spans shall be provided 
with portals of rigid design, which shall be as deep as the required 
clearance (Par. 52) will allow, and in the end posts proper pro- 
vision shall be made for the bending stresses produced by such 
portals. 

All the intermediate panel points in the top chord of through 
spans shall be provided with transverse struts with knee braces 
or with vertical sway bracing. The struts shall be made of 
four angles laced and shall have the same depth as the chord, 
to 'the upper and lower face of which they shall be riveted by 
means of connection plates. 

In the plane of the " loaded " chord ends of all bridges shall 
be provided with lateral struts where no end floor beams are used. 

Lateral, longitudinal and transverse bracing in all structures 
shall be composed of rigid members. 

84. Steel Trestles. Each trestle benl shall he composed of 
two columns braced together and, when battered, the batter 
shall generally not bo loss than 1 horizontal to 8 vertical or more 
than 1 horizontal to I vertical. 

The majority o\' the bents shall be united in pairs, forming 
a towel-, which shall he rigidly braced on all four sides and shall 
have four horizontal struts ;it its base. 

The column feet shall be secured to ihe foundations i>\ menus 






99 



STANDARD SPECIFICATIONS 



of details and anchor-bolts capable of resisting one and one- 
half (H) times the specified lateral (Pars. 62, 63) and longitu- 
dinal forces. (Pars. 64. 104.) 

85. Wooden Trestles. (See Pars. 285, 286, 287.) 

86. All Structures. Structures shall be so designed that all 
parts will be accessible for inspection, cleaning, and painting. 

Pockets or depressions which would hold water shall have 
drain holes, or be filled with waterproof material. 



Details of Desigx 

87. Minimum Size of Material. Xo rolled shape, except 
channels, or metal of less thickness than ^ in., shall be used 
except for fillers. The webs of channels shall not be less than 
i in. Xo angles shall be less than 2J"X2i"XA" and no rivets, 
except in beam connections, lattice and railings, shall be less 
than I in. in diam. (Pars. 95, 101.) 

88. Details of Joints. Main members of trusses shall be so 
arranged around the joints that their neutral axes will meet 
in a common point. 

The sections of top chords and inclined end posts generally 
consist of two rolled or built-up channels and a cover plate; such 
unsymmetrical sections must be so proportioned as to bring the 
neutral axis near the center of the webs. (Par. 90.) 

Abutting joints in compression members when faced for 
bearing shall be spliced en four sides sufficiently to hold the con- 
necting members accurately in place. 

All other joints in riveted work, whether in tension or in 
compression, shall be fully spliced. 

89. Details of Connections. The strength of connections 
shall be such as to cause the main member to fail should the 
combination be tested to destruction, (Par. 90.) 

Xo connection except for lattice bars or lattice angles shall 
have less than three rivets. - 

All joists and stringers shall preferably be attached to the 
floor beams by means of connecting angles and shall, wherever 
possible, rest upon shelf angles stiffened by vertical angles if 
necessary. The rivets, however, in such shelves shall not be 
assumed to carry any part of the shear. 

The calculated number of rivets connecting the stringers 



HIGHWAY BRIDGES 23 

to the floor beams and the floor beams to the trusses shall be 
increased by 25 per cent. 

Where sidewalks are placed outside the trusses, and supported 
on brackets, the connection shall preferably be made by means 
of a fully riveted tension plate, as no tension on rivet heads will 
be allowed. 

90. Riveted Work. In riveted work the main members shall 
be arranged, wherever practicable, so that the effective sectional 
area is placed symmetrically about the two principal neutral 
axes. (Par. 88.) 

Where two connected members have their centers of gravity 
in a continuous line the rivets in the splice plates must be arranged 
symmetrically about these, using the minimum pitch (Par. 34), 
and, by staggering or otherwise, have as few rivets as possible 
in planes parallel and perpendicular to the axis of the member. 

Where two members are connected by means of gusset plates 
the rivets must be arranged symetrically about both inter- 
secting center lines of gravity. 

The secondary stresses due to non-compliance with these rules 
must be provided for in the joint by increasing the area of splice 
or gusset plates and the number of rivets, or both. 

91. Rivet Spacing. (See Par. 34.) 

92. Edge Distance of Rivets. (See Par. 35.) 

93. Tension Members. In calculating the net area of tension 
members the area of rivet holes must be deducted, assuming 
the diameter of the hole -Jin. larger than the nominal size of the 
rivet. 

Main tension members shall be composed of sections placed 
symmetrically about the central piano through the truss. Sec- 
ondary tension members may be made of a single shape. (Par. 
72.) 

Pin-connected riveted tension members shall have a net 
section through the pin hole 25 per rent in excess of thai through 
the body of the main member. The minimum ne1 section back 
of the pin hole, parallel to the axis el' the member, shall net be 
loss than that through the body of the main member. 

94. Eye-bars. Heads of eye-bars shall In- forged ami -<> pro- 
portioned as to develop the full strength of the bar. (Par. 
43.) 

The eye-bars shall he placed in the i ins- so a- to be, as nearly 



24 STANDARD SPECIFICATIONS 

as possible, parallel to its central plane, the maximum inclina- 
tion of any bar being limited to 1 in. in 16 ft. 

Adjustable eye-bars, when used as counters, shall have the 
screw ends upset and shall be provided with turnbuckles. or with 
sleeve nuts provided with holes drilled through two opposite faces. 

95. Rods. All rods shall have the loop ends forged and, 
when used as counters, shall have the screw ends upset and shall 
be provided with turnbuckles or special sleeve nuts. (Par. 94.) 
The minimum size of all rods shall be one (1) sq.in. 

96. Compression Members. In compression members form- 
ing chord segments as much as possible of the metal shall be 
concentrated in the webs and flanges and the neutral axis shall 
be as near as possible to the center of the web. 

In all compression members the minimum thickness of each 
single web plate shall be one-fortieth (-£$) of the distance 
between the inner lines of rivets connecting it to the flanges, and 
when two or more plates form a compound web. the minimum 
thickness of each plate shall be ^ in. (Par. 34.) 

The minimum thickness of cover plates shall be one-forty- 
eighth (^) of the distance between rivet lines. 

The minimum thickness of flange angles, unsupported by 
cover plates, shall be one-sixteenth (^) of the width of the un- 
supported leg. 

No compression member shall have a length exceeding 120 
times its least radius of gyration, except those used for wind 
and lateral bracing, which may have a maximum length of 140 
times their least radius of gyration. 

97. Tie-Plates. (See Par. 40.) 

98. Lattice Bars. (See Par. 42.) 

99. Pins. (See Par. 43.) 

100. Pin Holes. (See Par. 44.) 

1 01. Column Bases in Trestles. Column bases shall be 
made of plates and shapes riveted together, and no cast bases or 
pedestals will be allowed, except when permitted by the engineer. 
(Par. 84.) 

Xo metal in the bases shall be less than one-half (h) in. in 
thickness and the base plates shall not be less than three-quarter 

(I) in. 

The bases shall be placed on all bearing surfaces and so 
anchored as to allow for expansion. 



HIGHWAY BRIDGES 25 

102. Anchor Bolts. (See Par. 46.) 

103. Camber. All through truss bridges shall be given 
a camber by making the panel length of the top chords, or their 
horizontal projections, longer than the corresponding panels 
of the bottom chord in the proportion of J' in. in 10 ft. 

104. Temperature. Provision shall be made for a free expan- 
sion and contraction of all parts, corresponding to a variation 
of 150° F. in temperature. 

For bridges less than 80 ft. in length one end shall be free 
to move upon smooth surfaces. 

Bridges of 80 ft. and over, resting on masonry, shall have 
hinged bolsters or shoes at both ends, and at one end the shoes 
shall rest upon a nest of turned expansion rollers, of not less than 
4 in. in diameter (Par. 69), moving between planed surfaces. 
(Par. 86.) 

In very high trestle towers one foot shall be fixed, two feet 
shall be fixed in one direction only, and the fourth shall be free 
to move in both directions. 



PART III 
RAILROAD BRIDGES* 

General Requirements 

105. Material. The material in the superstructure shall be 
structural steel, except rivets, and as may be otherwise specified. 

106. Clearances. On a straight line the clear height of 
through bridges shall not be less than 21 ft. above the top of 
rails for a width of 6 ft. over a single track, and the clear width 
shall not be less than 7 ft. from the center line of the track between 
the heights of 4 and 17 ft. above the rails. 

The width shall be increased to provide the same minimum 
clearance on curves, for a car SO ft. long, 14 ft. high, and 60 ft. 
center to center of trucks, allowance being made both for curva- 
ture and superelevation of rail. 

107. Cross Ties. (See Par. 283.) 

108. Guard Rails. (See Par. 2S4.) 

Loads 

109. Dead Load. The dead load shall consist of the estimated 
weight of the entire suspended structure. 

The approximate weight of the steelwork shall be obtained 
either by trial design or otherwise. 

The weight of the ballast shall be taken at 100 lbs. per cu.ft. ; 
the weight of the timber shall be taken at 4| lbs. per foot-board 
measure, with a minimum of 250 lbs. per lin.ft. of track, and of 
rails, fastenings, and splices at 150 lbs. per lin.ft. of track. 

no. Live Loads. The live loads, for each track, shall consist 
of two typical engines followed by a uniform load, according 

* Adapted from General Specifications for Steel Railroad Bridges. 1906, 
American Railway Engineering and Maintenance of Way Association. 
ti 26 



RAILROAD BRIDGES 



27 



to Cooper's series, or a system of loading giving practically 
equivalent stresses. The minimum loading shall be Cooper's 
E.40, as shown in the following diagrams: 



o © o 

o o 3 _ 

o o o o 

o o o o 



o o o o o 



o o o o 
o o o o 



8 8 



o o o o 



-^Q 



O Q O O ^ O 



o» in 4,000 lbs. per lin. ft. 



o o o o 



<^8- 



U^^*f4 ( -«^ fc --8^*4*lw5^^H« 



5^<-6-4MH»j*5- 



Fig. 1, 



or 



4,000 lbs, per lin. ft. 



Fig. 2. 

The diagram that gives the larger stresses shall be used. 

in. Heavier Loading. Heavier loadings shall be propor- 
tional to the above diagrams on the same spacing. 

ii2. Impact. An impact allowance shall be added to the com- 
puted maximum live load stresses, as follows: 



Impact = S 



300 



L + 300/' 



where S= Computed max. live-load stress, moment or shear. 

L= Loaded length of track in feet producing the maximum 

stress in the member. For bridges carrying more 

than one track the aggregate Length of all tracks 

producing the stress shall be used. 

No impact allowance shall be added to stresses produced by 

traction, centrifugal and lateral or wind forces. 

113. Lateral Force. All spans shall be designed for a lateral 
force on the " loaded " chord of 200 lbs. per lin. ft. plus 10 per 

cent of the specified train load on one Hack, and 200 lbs. per 

lin. ft. on the "unloaded" chord; these forces being considered 
as moving. 

114. Wind Pressure. Viaduct towers shall be designed for 
a force of 50 lbs. per sq.ft. on one and one-half (] ' I times the 
vertical projection of the structure unloaded; or 30 lbs. per 
sq.ft. on the same surface plus loo lbs. per lin. ft. oi structure 
applied 7 ft. above the rail for assumed wind load on train when 



28 



STANDARD SPECIFICATIONS 



the structure is either fully loaded or loaded on either track with 
empty cars, assumed to weigh 1200 lbs. per Unit., whichever 
gives the larger stress. 

115. Traction Force. Viaduct towers and similar structures 
shall be designed for a longitudinal force, applied to the rail, of 
20 per cent, of the live load. 

116. Centrifugal Force. Any structure located on a curve 
shall be designed to resist a lateral force of 10 per cent of the 
equivalent live load per lin.ft., applied 6 ft. above the top of 
rails. (Par. 112.) 

Unit Stres>e> 

117. Structural Steel. All parts of structures shall be so 
proportioned that the sum of the maximum stresses shall not 
exceed for structural steel and rivet steel the following values 
in lbs. per sq.in., except as modified in Paragraphs 122 to 124. 

(a) Axial tension, net section 16,000 lbs. 

(6) Bending, net section, on extreme fibers of rolled 

shapes, built sections, and plate girders 16,000 " 

Pins, on extreme fibers 24,000 " 

(c) Axial compression, gross section, 

S= 16000- 70- 
r 

where S= allowable unit stress, 

1= unsupported length of member in inches, 
r= Least radius of gyration of member in inches. (Par. 
143.) 

(d) Shear on: Turned bolts and field rivets, when 

hand driven 9.000 lbs. 

Field rivets, when power driven 11,000 " 

Shop-driven rivets and pins 12.000 " 

Plate girder webs, gross section 10,000 " 

(e) Bearing on: Turned bolts and field rivets, when 

hand driven 1S,000 " 

Field rivets, when power driven 22,000 " 

Shop-driven rivets and pins 24,000 " 

Expansion rollers, perlin.in 600f/ 

where d = Diameter of roller in inches. 



RAILROAD BRIDGES 29 

118. Pressure on Foundations. The pressure on . masonry 
foundations shall not exceed the following values in lbs. per 
square inch: 

Portland cement concrete 1:2:4 and first-class 
sandstone or limestone masonry, including 
impact 400 lbs. 

Portland cement concrete 1 :2 :0 (granitoid) and 

first-class granite masonry, including impact 600 " 

119. Pressure on Soils. For allowable pressures see Par. 20. 

120. Timber. For allowable stresses see Part VII. 

121. Cast Steel. For allowable stresses see Par. 70. 

122. Alternate Stresses. Members subject to alternate 
stresses of tension and compression shall be proportioned for 
the stress giving the largest section. 

If alternate stresses occur in succession during the passage 
of one train, as in stiff counters, each stress shall be increased 
by 50 per cent of the smaller. The connections shall in all cases 
be proportioned for the sum of the stresses. 

123. Counter-Stresses. Wherever the live- and dead-load 
stresses are of opposite character, only 70 per cent of the dead- 
load stress shall be considered as effective in counteracting the 
live-load stress. 

124. Combined Stresses. Members subject to both axial 
and bending stresses shall be proportioned so that the combined 
fiber stresses will not exceed the specified axial stresses. (Par. 
117.) 

For stresses produced by longitudinal and lateral or wind 
forces combined with those from live and dead load and cen- 
trifugal forces, the specified unit stresses (Par. L17) may be 
increased 25 per cent, provided that this combination gives a 
greater sectional area. 

Design of Sim en re. 

125. General Proportions. The width between centers of 
trusses shall in no case be less ihan one-t w cut ici h I ,\, | of the 
Span, nor less than is necessary to prevent overturning under 

tin 1 assumed lateral loading. 

Trusses shall preferably have a depth of nut less than one 



30 STANDARD SPECIFICATIONS 

tenth (j G ) of the span. Plate girders and rolled beams, used 
as girders, shall preferably have a depth of not less than one- 
twelfth (-3^) of the span. If shallower trusses, girders, or beams 
be used the section shall be increased so that the maximum deflec- 
tion will not be greater than if the above limiting ratios had not 
been exceeded. 

For general dimensions see Par. 75. 

126. Floor Framing. Stringers shall preferably be riveted 
to the webs of all intermediate floor beams by means of connection 
angles not less than ^ in. thick. Shelf angles, or other means 
provided to support the stringers during erection, shall not be 
considered as carrying any of the reaction. 

Floor beams shall preferably be arranged so as to be perpendic- 
ular to the girder or truss at the panel point, they may rest upon 
the top chord in deck bridges, but in through bridges they shall 
be riveted to the verticals. 

Where end floor beams are not used stringers resting on 
masonry shall have cross frames near their ends. These frames 
shall be riveted to girder or truss shoes where practicable. (Par. 
129.) 

127. Beam and Plate-Girder Bridges. (See Pars. 79, 125, and 
Part IV.) 

128. Pony Bridges. Pony trusses shall be riveted structures 
with double-webbed chords and shall have all web members 
latticed or otherwise effectively stiffened. (Par. 80.) 

129. Peck Bridges. Deck spans shall have transverse brac- 
ing at each end proportioned to carry the lateral load to the 
supports. (Par. 81.) 

130. Through Bridges. All trusses shall be so designed 
that the stresses may be determined with reasonable accuracy. 

The hip verticals and similar members, and the two end panels 
of the bottom chords of all single-track pin-connected trusses, 
and of all double-track trusses over 300 ft. span, shall be made 
rigid. 

Rigid counters are preferred, and where subject to reversal 
of stress shall preferably have riveted connections to the chords. 
Adjustable counters shall have open turnbuckles. 

131. Bracing. Lateral, longitudinal, and transverse bracing 
in all structures shall be composed of rigid members. 

Through truss spans shall have riveted portals which shall be 



RAILROAD BRIDGES 31 

rigidily connected to the end posts and the top chords. They 
shall be as deep as the clearance will permit. 

Intermediate transverse frames shall be used at each panel 
of through spans having vertical truss members where the 
clearance will permit. 

Lateral bracing shall be far enough below the flange to clear 
the ties. 

The minimum-sized angle to be used in lateral bracing shall 
be 3i"X3"X$' / - Not less tnan three rivets through the end of 
the angles shall be used at the connection. 

132. Steel Trestles. The struts at the foot of trestle towers 
shall be strong enough to slide the movable shoes when the track 
is unloaded. (Par. 84.) 

133. All Structures. Structures shall be so designed that 
all parts will be accessible for inspection, cleaning, and painting. 

Pockets or depressions which would hold water shall have 
drain holes, or be filled with waterproof material. 

Details of Design 

134. Minimum Size of Material. The minimum thickness 
of metal, except for fillers, shall be f in. 

Flanges of girders or built members without cover plate 
shall have a minimum thickness of one-twelfth (-^) of the width 
of the outstanding leg. (Par. 131.) 

135. Details of Joints. Main members of trusses shall be 
so arranged around the joints that their neutral axes will be as 
nearly as practicable in the center of the section and the neutral 
axes of intersecting main members shall meet in a common point. 

Abutting joints in compression members when faced for bear- 
ing shall be spliced on f< ur sides sufficiently to hold the connect- 
ing members accurately in piace. 

All other joints in riveted work, whether in tensi< n or in com- 
pression, shall be fully spliced. 

Where splice plates are not in direct contact with the parts 
which they connect rivets shall be used on each side o\ the joint 
in excess of the number theoretically required to the extent of 
one-third (J) of the number for each intervening plate. 

136. Details of Connections. The strength of connections 
shall be sufncienl to develop the full strength of the member, 



32 STANDARD SPECIFICATIONS 

even though the computed stress is less, the kind f si ss to 

which the member is subjected being considered. 

137. Riveted Work. 

138. Rivets. In proportioning rivets their nominal diameter 
shall be used. Rivets shall generally be | in. in diameter, and 
no rivets, except in lattice bars, shall be less than f in. in 
diameter. 

The diameter of the rivets in any angle carrying a calculated 
stress shall not exceed one-quarter (J) the width of the leg through 
which they are driven. In minor pans f-in. rivets may be used 
in 3-in. angles and f-in. rivets in 2^-in. angles. 

Rivets carrying a calculated stress and whose grip exceeds 
four diameters shall be increased in number, at least 1 per cent 
for each additional ^ in. of grip. 

Rivets carrying stress and passing through fillers shall be 
increased 50 per cent in number, and the excess rivets, when 
ssible, shall be outside the connected member. 

Riv ts nnecting flanges and lattice bars shall have si 3 
as follows: J-in. rivets in flanges 3^ in. wide and over. f-in. rivets 
in flanges from 2h to 3^ in., and f-in. rivets in flanges less than 
2^ in. wide. 

139. Rivet Spacing. The minimum distance between cen- 
3 of rivet holes shall be three diameters of the rivet an 

possible, not less than 3 in. for |-in. rivets and 2^- in. for f-in. 
rivets. The maximum pitch, in the direction of the stre— : 1 
members composed of plates and shapes, shall be 6 in. for |-in. 
rivets and 5 in. for f-in. rivets. For angles with two gauge 
lines and rivets staggered the maximum shall be twice the above 
in each line. 

Where two or more plates are used in contact, rivets not more 
than 12 in. apart in either direction shall be used to hold the 
plates together. 

In tension members composed of two angles in contact a pitch 
of 12 in. will be allowed for riveting the angles together. 

The maximum pitch at ends of built-up compression mem- 
bers shall not exceed four diameters of the rivet for a length 
equal to two times the width of the members. 

140. Edge Distance of Rivets. The minimum distance 
from the center of any rivet hole to a sheared edge shall be li in. 

;-in. rivets and 1^ in. for f-in. rivets, and to a rolled edge 






RAILROAD BRIDGES 33 

1J in. and 1J in. respectively. The maximum distance from 
any edge shall be eight (8) times the thickness of the outside 
plate, but shall not exceed 5 in. 

141. Tension Members. In calculating the net area of ten- 
sion members the area of rivet holes must be deducted, assum- 
ing the diameter of the hole to be J- in. larger than the nominal 
size of the rivet. 

Pin-connected riveted tension members shall have a net 
section through the pin hole 25 per cent in excess of that through 
the body of the main member. The minimum net section back 
of the pin hole, parallel to the axis of the member, shall not be 
less than that through the body of the main member. 

142. Eye-bars. The eye-bars composing a member shall be 
so arranged that adjacent bars shall not have their surfaces in 
contact; they shall be, as nearly as possible, parallel to the cen- 
tral plane of the truss, the maximum inclination of any bar 
being limited to 1 inch in 16 ft. 

Adjustable eye-bars, when used as counters, shall have the 
screw ends upset and shall be provided with turnbuckles, or 
with sleeve nuts provided with holes drilled through two opposite 
faces. 

143. Compression Members. In compression members form- 
ing chord segments as much as possible of the metal shall be 
concentrated in the webs and flanges and the neutral axis shall 
be as near as possible to the center of the web. 

In all compression members the minimum thickness of each 
single web plate shall be one-thirty-second (^) of the distance 
between the inner lines of rivets connecting it to the flanges 
and, when two or more plates form a compound web, the min- 
imum thickness of each plate shall be ^ in. (Par. 139.) 

The minimum thickness of cover plates shall be one-fortieth 
(^ ) of the distance between rivet lines. 

No compression member shall have a length exceeding 100 
times its least radius of gyration, except those used for wind 
and lateral bracing, which may have a maximum length of L20 
times their least radius of gyration. 

Forked ends on compression members will be permitted only 
where unavoidable; where w^vd a sufficient number of pin plates 

shall be provided to make the jaws of twice the sectional area 
of the main member. At least one of these plates shall extend 



34 STANDARD SPECIFICATIONS 

to the far edge of the farthest tie-plate and the remainder not 
less than 6 in. beyond the near edge of the same plate. 

144. Tie-plates. The open sides of compression members 
shall be stayed by diagonal lattice having tie-plates as near 
each end as practicable and at intermediate points where the 
lattice is interrupted. In main members the end tie-plates 
shall have a length not less than the distance between the lines 
of rivets connecting them to the flanges, and intermediate tie- 
plates not less than one-half (J) this distance. Their thickness 
shall not be less than one-forty-eighth (fa) of the same dis- 
tance. 

145. Lattice Bars. Single lattice bars shall have an inclina- 
tion of approximately 60 degrees with the axis of the main mem- 
ber and shall have minimum thickness of one-fortieth (-fa) of 
the distance between the rivets connecting them to the member. 
Single lattice bars may be connected with one rivet, except in 
flanges more than 5 in. wide, where two rivets shall be used. 

Double lattice bars shall be used where the distance between 
rivet lines in the flanges exceeds 15 in. They shall have a 
minimum thickness of one-sixtieth (fa) of the distance between 
the rivets connecting them to the member, shall have an inclina- 
tion of approximately 45 degrees, and shall be riveted at their 
intersection. 

Lattice bars shall be so spaced that the portion of the flange 
included between their connection shall be as strong as the 
member as a whole. 

Instead of lattice bars shapes of equivalent strength may be 
used and where angles are used they shall be connected by at 
least two rivets. 

The minimum width of lattice shall be: 2\ in. for J in. -rivets, 
2\ in. for J in. -rivets and 2 in. for f in. -rivets. 

146. Pins. The minimum diameter of pins shall be eight- 
tenths (fa) of the width of the widest eye-bar attached thereto. 

Members shall be packed on pins, using filling rings where 
necessary, in a manner that will prevent any lateral movement. 

Pins shall be long enough to insure a full bearing of all the 
parts connected upon the turned body of the pin. They shall 
be secured by chamfered nuts or be provided with washers if 
solid nuts are used. The screw ends shall be long enough to 
admit of burring the threads. 



RAILROAD BRIDGES 35 

147. Pin Holes. Pin holes shall be reinforced by plates 
where necessary, and at least one plate shall be as wide as the 
flanges will allow and be on the same side as the angles. They 
shall contain sufficient rivets to distribute their portion of the 
pin pressure to the full cross-section of the main member. 

148. Bolts. Where members are connected by bolts the 
turned body of these shall be long enough to extend through 
the metal. A washer at least J in. thick shall be used under the 
nut. Bolts shall not be used in place of rivets except by special 
permission. Heads and nuts shall be hexagonal. 

For anchor bolts see Par. 46. 

149. Column Bases in Trestles. (See Par. 101.) 

150. Camber. Ordinary truss spans shall be given a camber 
by making the panel length of the top chords, or their horizontal 
projections, longer than the corresponding panels of the bottom 
chord in the proportion of -g- in. in 10 ft. For truss spans of 
unusual length or loading, draw spans, cantilevers, etc., the 
camber shall be obtained from the calculated distortion of the 
various members under their assumed stress. 

151. Bearings. Bearing plates may be of cast steel or built 
up. All bearing plates, built-up pedestals and built-up bolsters 
or shoes shall be so designed and set upon the masonry that the 
load will be distributed over the entire bearing area without 
causing any of the parts to be overstressed. 

Movable bearings shall be designed to permit motion in one 
direction only; fixed bearings shall be firmly anchored to the 
masonry. 

Bridges on inclined grade without pin shoes shall have the 
sole plates beveled so that the masonry and expansion surfaces 
may be level. 

152. Temperature. Provision shall be made for a free expan- 
sion and contraction of all bridge structures to the extent 
of -J- inch for each 10 ft. in length. Efficient means shall be 
provided to prevent excessive motion at any one point. 

For bridges loss than 80 ft. in length one end shall be free to 
move upon smooth surfaces. 

Bridges of 80 ft. and over, resting on masonry, shall have 
hinged holsters or shoes at both ends. At one end the shoes 
sh;ill rest upon a nest of turned expansion rollers, or rockers may 
be used for the same purpose. 



3G STANDARD SPECIFICATIONS 

Expansion rollers shall not be less than 4 in. in diameter. 
(Par. 117c.) They shall be coupled together with substantial side 
bars which shall be so arranged that the rollers can be readily 
cleaned. (Par. 133. 

In very high trestle towers one foot shall be fixed, two feet 
shall be fixed in one direction only, and the fourth shall be free 
to move in both directions. 



PART IV 

PLATE GIRDERS 

153. General Requirements. (See Pars. 49-58 and 105-10S.) 

154. Loading. The loading upon plate girders shall be 
taken, when used in 

Buildings, from Pars. 1, 2 and 8-11; 
Highway bridges, from Pars. 59-64; and 
Railroad bridges, from Pars. 109-116. 

155. Unit Stresses. All parts of plate girders, or plate-girder 
bridges, shall be so proportioned that the sum of the maximum 
stresses shall not exceed for structural steel and rivet steel the 
following values in pounds per square inch, except as modified 
in Par. 124. 

(a) Axial tension, net section 16,000 lbs. 

(b) Bending, net section of tension flange (Par. 163) . . . 16,000 " 

Pins, on extreme fibers 24,000 " 

(c) Axial compression, gross section, 

S = 16,000 -70-, 
r 

where ^—allowable unit stress, 

/—unsupported length of member in inches (Par. L67), 
r=lcast radius of gyration of member in inches. (Pars. 
39, 96 and 143.) 

(d) Shear on: Turned bolts and field rivets, when hand 

driven 9.000 lbs. 

Field rivets, when power driven 1 1,000 

Shop-driven rivets and pins 12,000 

Webs of girder, gross section 10,001) 



38 STANDARD SPECIFICATIONS 

(e) Bearing on: Turned bolts and field rivets when 

hand driven 18,000 " 

Field rivets when power driven 22,000 " 

Shop-driven rivets and pins. . ' 24,000 " 

Expansion rollers, per lin. inch 600c? 

where d = diameter, of roller in inches. 

(/) For girders in buildings the above unit stresses for 
rivets and pins shall be reduced 16f per cent. 
(g) For combined stresses see Par. 124. 

For allowable unit stresses in cast steel see Par. 

70. 
For allowable pressures on walls and masonry 

foundations see Pars. IS and 66. 
For allowable pressures on soils see Par. 20. 

156. General Proportions. The width between centers of 
girders in deck bridges, carrying a single straight electric railway 
or railroad track, shall generally be as follows: 

For spans up to 60 feet inclusive 6' 6" 

" " from 60 feet to SO " " 7' 0" 

" " " SO " and over 7' 6" 

In through bridges the girders shall generally be spaced so 
as to give a clear width of 10 ft. at the top of rails increasing to 
14 ft. at a height of 4 ft. above same. 

For additional clearance on curves see Pars. 52 and 106. 

The depth of plate girders in buildings shall preferably not 
be less than one-sixteenth (^) of the span, or hi bridges less 
than one twelfth (^.) of the span and, if shallower girders be 
used, the section be increased so that the deflection will not be 
greater than if the above limiting ratios had not been exceeded. 

For general dimensions see Par. 75. 

157. Through Bridges. Through plate girders shall have 
their top flanges stayed at each end of every floor beam, or in 
case of solid floors, at distances not exceeding 12 ft., by knee 
braces or gusset plates stiffened by angles. 

Where flooring or ties are supported on shelf angles riveted 
to the webs of the girders these angles shall have a minimum 






PLATE GIRDERS 39 

thickness of f in. and shall have their outstanding leg not over 
3^- in., unless they are supported by stiff eners at intervals not 
over 30 in. Such shelf angles shall not be considered as a part of 
the flange. 

Through plate girders shall preferably have their upper comers 
neatly rounded off to a radius not exceeding 3 ft., or less than 
one-third (J) of the depth of the girder. 

Where the bridge is composed of two or more spans only the 
corners at the extreme ends need be rounded, unless the girders 
vary in depth, in which case the deeper ones shall have their top 
flanges rounded to meet the corner of the adjacent girder. (Par. 
163.) 

158. Skew Bridges. Ends of deck-plate girders, and in 
through bridges ends of track stringers at abutments, shall be 
square to the track, unless a ballasted floor be used. 

159. Design of Girder. Plate girders shall be designed either 
by the moment of inertia of their net section, or by assuming that 
the flange areas are concentrated at their centers of gravity, in 
which case one-eighth (J) of the gross section of the web, if 
properly spliced, may be used as flange section. 

160. Design of Flanges. In girders having flange plates the 
total flange area shall be so divided that forty per cent (40%) 
or more will be concentrated in the flange angles and side plate-. 
if any, and the remainder in the cover plates. 

Where two or more cover plates are used they shall be of 
equal thickness, or shall decrease in thickness outward from 
the angles. 

161. Flange Plates. The flange plates of all girders shall be 
limited in width, so as not to extend beyond the outer lines of 
rivets connecting them to the angles more than 8 times the thick- 
ness of the outside plate, or more than 5 in. (Par. 171.) 

All cover plates shall extend at each end at least 12 in. beyond 
the points where they might he cut off theoretically. 

162. Flange Splices. Mange splices, where unavoidable, 
shall be located at points where there is a considerable excess of 
sectional area. Mange angles and flange plates shall all break 
joints so that no two pieces will be spliced within IS in. i)( each 

other. In general no held splices will be allowed in girders less 
than 70 feet long; this provision, however, does not apply to 
work intended for export. (Par. loo.) 



40 STANDARD SPECIFICATIONS 

163. Compression Flange. The gross section of the compres- 
sion flange shall not be less than the gross section of the tension 

_ . The unsupported length of the flange shall generally 
16 times its width in buildings, or 12 times its width 
in r ges 

Where the unsupported length exceeds these ratios the flange 
shall be considered as a column between the points of sup- 

The compression flanges of girders without cover plates shall, 
in buildings, have a minimum thickness of one-sixteenth ^ 
of the width of the outstanding leg. and in bridges a minimum 
thickness of one-twelfth .'-- . 

In bridges, where cover plates are used, one plate of the top 
flange shall extend the whole length of the girder. In through 
bridges this plate, or a plate of the same width, shall be extended 
over the rounded corners and be continued down, either below 
the corners of the adjacent girders, or at the extreme ends of the 
bridges down to the bottom of the girder. (Par. 1-57. 

164. Flange Rivets. The flanges of plate girders shall be 
connected to the web with a sufficient number of rivets to trans- 
fer the calculated shear at any point, in a distance equal to the 
distance between centers of gravity of rivet lines at that point, 
combined with any load that is applied directly on the flange. 

The wheel loads, where rails rest directly on the flange, shall 
—umed to be distributed over 30 in.: where the ties rest on 
the flanges the wheel loads shall be assumed to be distributed over 
three ties. Pars. 171. 283. 

165. Design of Web. The web shall be designed for the total 
maximum shear, assuming this to be uniformly distributed over 

its _. 3£ 

166. Web Splices. When necessary to splice the web the 
splice plates and the number of rivets shall be sufficient to resist 
the maximum stress - -ulting from a combination of bending 
and shear at that point. (Par. 171 

167. Web Stiffeners. Web stiffeners shall be located in pairs 
at the ends and inner edges of bearings and at points of concen- 

I loads, their area to be determined by the formula: 



S=16,000— 7 - 

r 






PLATE GIRDERS 41 

where S= allowable unit stress. 

1 = one-half the depth of girder in inches. 
r= Radius of gyration of angles, neglecting fillers and 
inclosed portion of web. 

End stiffeners, those under concentrated loads and at web splices, 
shall be on fillers and have their outstanding legs as wide as the 
flange angles will allow and shall fit tightly against them. 

Where the thickness of the web is less than one-sixty-fourth 
( Jj) of its depth between inner rivet lines intermediate stiffeners 
shall be used. 

The intermediate stiffeners shall be spaced by the formula: 



For girders in buildings rf<64/ 
For girders in bridges d^Q4t 



< 



16000\ 

Q ) 

12000 X 



where d= distance in inches between centers of stiffeners, with a 
maximum distance equal to the depth of the girder, or 
64 in. 
t= thickness of web in inches; 
Q = shear in web per square inch. 

Intermediate stiffeners may be offset (crimped), and their out- 
standing legs shall not be less than one-thirty-second (^. 2 ) of the 
depth of the girder plus 2 in. 

168. Bracing. All deck-plate girder bridges shall have lat- 
eral bracing near the plane of the top chord, but far enough 
below the flanges lo clear the ties, and those having a span of 
60 ft. or over shall in addition have lateral bracing in the plane 
of the bottom chord. Cross frames shall be located near each 
end and at intermediate points not exceeding 20 ft. 'The lateral 
system shall generally be of the single cancellation type. 

Through-plate girder spans, not having a solid floor, shall 
have a single system of stringer bracing and a lateral, double- 
intersection system of bracing in the plane of the bottom chord. 

All bracing shall he composed of rigid members. (Par L31.) 

169. Minimum Size of Material. The minimum thickness 
of metal, excepl for fillers, shall he lor girders in building or 



42 STANDARD SPECIFICATIONS 

highway bridges ^ in. with f-in. rivets, and for girders in railroad 
bridges -| in. with f-in. rivets. 

170. Rivets. In proportioning rivets their nominal diameter 
shall be used. The diameter of the rivets in any angle carrying 
a calculated stress shall not exceed one-quarter (^) the width 
of the leg through which they are driven. Rivets carrying a 
calculated stress and whose grip exceeds four diameters shall 
be increased in number, at least one per cent for each additional 
Jg in. of grip. 

171. Rivet Spacing. The minimum distance between cen- 
ters of rivet holes shall be three diameters of the rivet and, if 
possible, not less than 3 in. for j-in. rivets and 2h in. for f-in. 
rivets. In the flanges the maximum pitch, in the direction of the 
stress, shall be 6 in. for f-in. rivets and 5 in. for J-in. rivets. 
For angles with two gauge lines and rivets staggered the maxi- 
mum shall be twice the above in each line. Cover plates more 
than 16 in. wide shall have four lines of rivets. (Pars. 161 
and 164.) 

The maximum pitch at ends of cover plates shall not exceed 
four diameters of the rivet for a length equal to two times the 
width of the plate. 

The maximum pich in stiffeners shall be determined by the 
loading, if any. but shall in no case exceed 44 in. The vertical 
web splice shall, where no horizontal plates are used, have at 
least two rows of rivets on each side of the joint with the above 
maximum pitch. 

172. Edge Distance. (See Par. 140.) 

173. Bearings. (See Par. 151.) 

174. Temperature. (See Par. 152.) 



PART Y 

MATERIALS AND WORKMANSHIP 



Materials for Structural and Rivet Steel 

175. Process of Manufacture. Steel shall be manufactured 
by the open-hearth process. 

176. Schedule of Requirements. The chemical and physical 
properties shall conform to the following limits, except as modified 
in Pars. 177 to 180. The yield point, as indicated by the drop 
of beam, shall be recorded in the test reports. 



Elements Considered. 


Structural Steel. 


Rivet Steel. 


Cast Steel. 


•nu u / Basic 

Phosphorus, max. < ^ ^ 
Sulphur maximum 


0.04% 
0.06% 

0.05% 

Desired 
60,000 

l,500,000f 


0.04% 
0.04% 
0.04% 

Desired 
50,000 

1,500,000 


0.05% 
0.08% 
0.05% 

Not less than 
65.000 

J 15% 

silky or fine 
granular. 
in 90°, d=3 


Ultimate tensile strength • 
in pounds per square 
inch* 

Elongation, min. % in 8 
in., Fig. 3 

Elongation, min. in 2 in./ 
Fig.4 

( Jharacter of fracture 

Cold bends without frac- 
lure 


f 

[ 
1 


Ult. tensile 
strengl h 

22% 

"silky 
L80° flat:!: 


Ult. tensile 
strength 

silky 
isu flat§ 



177. * Allowable Variations. If the ultimate strength varies 
more than 1000 lbs. from thai desired a retest shall be made 
on the same gauge, which, to be acceptable, shall be within 5000 
lbs. of the desired ultimate. 

178. 1 Modification in Elongation. For material less titan 
■' (> in. and more than , ; in. in thickness the following modifica- 
tions will be allowed in the requirements for elongation: 

1.; 



44 STANDARD SPECIFICATIONS 

F i ach ^ inch in thickni ss w ^ in. a deduction 

of 2^y will be allowed from the specified percentage. 
For each J in. in thickness above f in. a deduction of 
1 will be allowed from the specified percentage. 
179.: Bending Tests. Bending tests may be made by 
y blows. Plates, shapes, and bars less than 1 in. 
thick shall bend as called for in Par. 176. 

Full-sized material for eye-bars and other steel 1 in. thick 
and o\ tesl as ] >lled, shall bend cold 180 degrees around a 
pin. the diameter of which is equal to twice the thickm :— 
the bar, without any fracture on the outside of bend. 

Angles f in. and less in thickness shall open flat, and angles 
i in. and less in thickness shall bend shut, when cold, under 
blows of a hammer, without sign of fracture. This test will be 
made only when required by the inspe cl 

i8o.§ Nicked Bends. Rivet steel, when nicked and bent 
around a bar of the same diameter of the rivet rod. shall give 
a gradual break and a fine, silky, unifonn fracture. 

181. Chemical Analyses. Chemical determinations of the 
percentages of carbon, phosphorus, sulphur and manganese shall 
be made by the manufacturer from a test ingot taken at the time 
of the pouring of each melt of steel and a correct copy of such 
analysis shall be furnished to the Engineer or his inspector. Check 
analyses shall be made from finished material, if called for by the 
purchaser, in which case an exce— : 25 per cent, above the 
required limits will be allowed. 

182. Form of Specimens. 

Plati S and Bars: Specimens for tensile and 

bending tests : ■: plates, shapes and bars shall be made 



. ~._ ■ Parallel Section 



A\ JOI 1: 



About 2 



Fig. 3. 
by cutting coupons from the finished product, which 



MATERIALS AND WORKMANSHIP 



45 



shall have both faces rolled and both edges milled to 
the form shown by Fig. 3; or with both edges parallel; 
or they may be turned to a diameter of f in. for a length 
of at least 9 in. with enlarged ends. 

(6) Rivets: Rivet rods shall be tested as rolled. 

(c) Pins and Rollers : Specimens shall be cut from the finished 
rolled or forged bar, in such a manner that the center 
of the specimen shall be 1 in. from the surface of the 
bar. The specimen for tensile test shall be turned to 




X~ 



Fig. 4. 



the form shown in Fig. 4. The specimen for bending 
test shall be 1 in. by \ in. in section. 
(d) Cast Steel. The number of tests will depend on the 
character and importance of the castings. Specimen 
shall be cut cold from cupons molded and cast on some 
portion of one or more castings from each melt or from 
the sink heads, if the heads are of sufficient size. The 
coupon o)- sink head, so used, shall be annealed with the 

casting before it is cut off. Test specimens to lie of the 
form prescribed for pins and rollers. 

183. Annealed Specimens. Material which is to he used 
without annealing or further treatment shall bo bested in the 
condition in which it conies from the rolls. When material is 
to be annealed, or otherwise treated before use, the specimens 
lor tensile tests representing such material shall l>e cut from prop- 
erly annealed or similarly treated short lengths o\' the full section 
of the bar. 

184. Number of Tests. At least one tensile and one bending 
test shall he made from each moll of steel as rolled. In case 



46 STANDARD SPECIFICATIONS 

steel differing | in. and more in thickness is rolled from one melt 
a test shall be made from the thickest and thinnest material 
rolled. 

185. Finish. Finished material shall be free from injurious 
seams, flaws, cracks, defective edges, or other defects, and have 
a smooth, uniform, and workmanlike finish. Plates 36 in. in 
width and under shall have rolled edges. 

186. Stamping. Every finished piece of steel shall have 
the melt number and the name of the manufacturer stamped 
or rolled upon it. Steel for pins and rollers shall be stamped 
on the end. Rivet and lattice steel and other small parts 
may be bundled with the above marks on an attached metal 
tag. 

187. Defective Material. Material which, subsequent to the 
above tests at the mills, and its acceptance there, develops weak 
spots, brittleness, cracks or other imperfections, or is found to 
have injurious defects, will be rejected at the shop and shall be 
replaced by the manufacturer at his own cost. 

188. Allowable Variation in Weight (when ordered to weight). 
A variation in cross-section or weight of each piece of steel of 
more than 2\ per cent from that specified will be sufficient cause 
for rejection, except in case of sheared plates, which will be 
covered by the following permissible variations applying to single 
plates only: Plates under 12^ lbs. per sq.ft. 

(a) I T p to 75 in. wide, 2\ per cent above and below the pre- 

scribed weight. 

(b) 75 in. and up to 100 in. wide, 5 per cent above or 3 per 

cent below. 

(c) 100 in. wide and over, 10 per cent above or 3 per cent 

below. 
Plates 12^ lbs. per sq.ft. or heavier. 

(d) Up to 100 in., 2-J- per cent above or below. 

(e) 100 in. wide and over, 5 per cent above or below. 

189. Allowable Variation in Weight (when ordered to gauge). 
Plates will be accepted if they do not measure more than 0.01 
in. below the ordered thickness. 

An excess over the nominal weight, corresponding to the 
dimensions on the order, will be allowed for each plate, if not 
more than that shown in the following table, one cubic inch of 
rolled steel being assumed to weigh 0.2833 lb. 



MATERIALS AND WORKMANSHIP 



47 



Thickness 
Ordered. 


Nominal 
Weights. 


Width of Plate. 










Inch. 


Pounds. 


Up to 75". 


7.5" and up 
to 100". 


100" and up 
to 115". 


Over 115". 


1 

4 


10.20 


10 % 


14 % 


18 % 




A 


12.75 


8 % 


12 % 


16 % 




3 

¥ 


15.30 


7 % 


10 % 


13 % 


17% 


7 
T6 


17.85 


. 6 % 


8 % 


10 % 


13% 


* 


20.40 


5 % 


7 % 


9 % 


12% 


& 


22 . 95 


H% 


6J% 


^'; 


11% 


1 


25 . 50 


4 % 


6 % % 


10% 


over | 




3*% 


5 % 6*% 


9% 



190. Cast Iron. Except where chilled iron is specified, cast- 
ings shall be made of tough gray iron 7 with sulphur not over 
0.10 per cent. They shall be true to pattern, out of wind and 
free from flaws and excessive shrinkage. If tests be demanded 
they shall be made on the "Arbitration Bar " of the American 
Society for Testing Materials, which is a round bar 1-|- in. in diam- 
eter and 15 inches long. The transverse test shall be made on a 
supported length of 12 in. with a load at middle. The minimum 
breaking load so applied shall be 2900 lbs. with a deflection of 
at least ^ in. before rupture. 

191. Wrought-Iron Bars. Wrought iron shall be double 
rolled, tough, fibrous, and uniform in character. It shall be 
thoroughly welded in rolling and be free from surface defects. 
When tested in specimens of the form of Fig. 3, or in full-sized 
pieces of the same length, it shall show an ultimate strength oi 
at least 50,000 lbs. per sq.in., an elongation of a1 least L8 per 
cent in 8 inches, with fracture wholly fibrous. Specimens shall 
bend cold, with the fiber, through L35 degrees, without sign o( 
fracture, around a pin the diameter of which is uot over twice 
the thickness of the piece tested. When nicked and bent, the 
fracture shall show at least 90 per cent fibrous. 

Materials foe Concrete Reinforcement Bai 

192. Process of Manufacture. Steel may be made l>\ either 
the open-hearth or Bessemer process. \\-m< shall be rolled from 

billets. 



As adopted by The Association of \i 



Sic. I Manufact urcrs, I'.'lo 



4s 



STANDARD SPECIFICATION* 



193. Schedule of Requirements. The chemical and physical 
properties shall conform to the following limits: 



-Steel Grade. Hard-Steel Grade. 



Elements Considered. 



Plain 
Bars. 



Deformed 
Bars. 



Plain 
Bars. 



Deformed 
Bars. 



Cold- 
twisted 
Bars. 



Phosphorus. Bessemer . . . 

max. •:• en-hearth , 

Ultimate tensile strength, 

lbs. per sq.in. 
Yield point, minimum, lbs. 

per sq.in. 



Elongation, min. 
8 inches 



0.10% 
0.06% 

oo.OOO to 
70.000 

33.000 

1.400.000 



0.10% 
0.06% 

55.000 to 
70.000 

33.000 

1.250.000 



0.10% 
06% 

S0,000 mi 

50.000 
1.200.000 



10^ c 
0.06% 

SO. 000 min. 

50,000 
1.000,000 



per cent in 



Cold bends without fracture: 
Bars under f" in. diam. or 

thickness 
Bars $'' in. diam. or thick- \ 

ness and over 



Ult. tensile 
strength 






- 



Ult. tensile 
strength 

180°, d = t 



Ult. tensile 
strength 



1So : . d=3t 
90°. d=3t 



Ult. tensile 
strength 



180°. d=±t 
90°. d = -it 



0.10% 

0.06% 

Recorded 

only 

55,000 



180°, d = 2t 
180°, c/ = 3r 



The hard-steel grade will be used only when specified. 

194. Chemical Determinations. In order to determine if 
the material conforms to the chemical limitations prescribed in 
Par. 193, analysis shall be made by the manufacturer from a 
test ingot taken at the time of the pouring of each melt or blow 
of steel, and a correct copy of such analysis shall be furnished 
to the engineer or his inspector. 

195. Yield Point. For the purpose of these specifications, 
the yield point shall be determined by careful observation of the 
drop of the beam of the testing machine, or by other equally 
accurate methods. 

196. Form of Specimens. 

(a) Tensile and bending-test specimens may be cut from 
the bars as rolled, but tensile and bending-test specimens 
of deformed bars may be planed or turned for a length 
of at least 9 in. if deemed necessary by the manufacturer 
in order to obtain uniform cross-section. 

(6) Tensile and bending-test specimens of cold-twisted bars 
shall be cut from the bars after twisting, and shall be 
tested in full size without further treatment, unless 
otherwise specified as in (c), in which case the conditions 
therein stipulated shall govern. 

(c) If it is desired that the testing and acceptance for cold- 
twisted bars be made upon the hot-rolled bars before 



MATERIALS AND WORKMANSHIP 49 

being twisted, the hot-rolled bars shall meet the require- 
ments of the structural-steel grade for plain bars shown 
in this specification. 

197. Number of Tests. At least one tensile and one bending 
test shall be made from each melt of open-hearth steel rolled, 
and from each blow or lot of ten tons of Bessemer steel rolled. 
In case bars differing § in. and more in diameter or thickness 
are rolled from one melt or blow, a test shall be made from the 
thickest and thinnest material rolled. Should either of these test 
specimens develop flaws, or should the tensile-test specimen 
break outside of the middle third of its gauged length, it may 
be discarded and another test specimen substituted therefor. 
In case a tensile-test specimen does not meet the specifications, 
an additional test may be made. 

The bending test may be made by pressure or by light blows. 

198. Modifications in Elongation for Thin and Thick Material. 
For bars less than ^ in. and more than J in. nominal diameter 
or thickness, the following modifications shall be made in the 
requirements for elongations: 

(u) For each increase of -§■ in. in diameter or thickness above 

f in., a deduction of one shall be made from the specified 

percentage of elongation. 
(/>) For each decrease of ^ inch in diameter or thickness 

below ^ in., a deduction of one shall be made from the 

specified percentage of elongation. 
(c) The above modifications in elongation shall not apply 

to cold-1 wisted bars. 

199. Number of Twists. Cold-twisted bars shall be twisted 
cold with one complete twist in a length equal bo not more than 
12 times the thickness of the bar. 

200. Finish. Material must be free from injurious seams, 
flaws, or cracks, and have a workmanlike finish. 

201. Variation in Weight. Bars for reinforcement arc subject 
to rejection if the actual weight of an\ lot varies more than 5 
per cent over or under 1 he theoretical weight i^i that lot. 

\Y( iRKM \ NSH] i' 

202. General. All parts forming a structure shall he built 
in accordance with approved drawings. The workmanship and 
finish shall be equal i»> the best practice in modern bridge work-. 



50 STANDARD SPECIFICATIONS 

203. Straightening Material. Material shall be thoroughly 
straightened in the shop by methods that will not injure it, before 
being laid off or worked in any way. 

The several pieces forming one built member shall be straight 
and fit closely together, and finished members shall be free from 
twists, bends or open joints. 

204. Lattice Bars. Lattice bars shall have neatly rounded 
ends, unless otherwise called for. 

205. Finish. Shearing shall be neatly and accurately done 
and all portions of the work exposed to view neatly finished with 
sharp cutting tools, a chisel, or a file. 

206. Edge Planing. In all material over -| in. thick the sheared 
edges or ends shall be planed at least J in. 

207. Finish of Joints. Abutting joints shall be cut or dressed 
true and straight and fitted close together, especially where open 
to view. In compression joints, depending on contact bearing, 
the surfaces shall be truly faced, so as to have even bearings 
after they are riveted up complete and when perfectly aligned. 

208. Field Connections. Holes for floor beam and stringer 
connections shall be sub-punched and reamed according to Par. 
212 to a steel templet one inch thick. 

All other field connections, except those for laterals and sway 
bracing, shall be assembled in the shop and the unfair holes 
reamed; and when so reamed the pieces shall be match-marked 
before being taken apart. 

209. Connection Angles. Connection angles for floor beams, 
stringers, and plate girders shall be flush with each other and 
correct as to position and length of girder. 

When not correct after being riveted up milling will be required 
and the removal of more than ^ in. from their thickness will be 
cause for rejection. 

210. Rivet Holes. When reaming is not required the diameter 
of the punch, shall not be more than ^ in. greater than the 
diameter of the rivet; nor the diameter of the die more than 
J in. greater than the diameter of the punch. (Pars. 212 
and 214.) 

211. Punching. All punching shall be accurately done. Drift- 
ing to enlarge unfair holes will not be allowed. If the holes must 
be enlarged to admit the rivet, they shall be reamed. Poor 
matching of holes will be cause for rejection. (Par. 212.) 



MATERIALS AND WORKMANSHIP 51 

212. Sub-punching and Reaming. All material more than 
-§- in. thick shall be sub-punched and reamed or drilled from the 
solid. 

When reaming is required the punch used shall have a diameter 
not less than ^ in. smaller than the nominal diameter of the rivet . 
Holes shall then be reamed to a diameter not more than ^ in. 
larger than the nominal diameter of the rivet. All reaming shall 
be done with twist drills. (Pars. 208, 213.) 

213. Burrs. The outside burrs on reamed holes shall be 
removed. 

214. Reaming after Assembling.* When general reaming is 
required it shall be done after the pieces forming one built mem- 
ber are assembled and firmly bolted together. If necessary to take 
the pieces apart for shipping and handling the respective pieces 
reamed together shall be so marked that they may be reassembled 
in the same position in the final setting up. No interchange of 
reamed parts will be allowed. 

215. Size of Rivets. The size of rivets, called for on the 
plans, shall be understood to mean the actual size of the cold 
rivet before heating. 

216. Rivets. Rivets shall be driven by pressure tools 
wherever possible. Pneumatic hammers shall be used in prefer- 
ence to hand driving. 

217. Field Rivets. Field rivets shall be furnished to the 
amount of 15 per cent plus ten rivets in excess of the nominal 
number required for each size. 

218. Turned Bolts. Wherever bolts arc used in place of 
rivets which transmit shears the holes shall be reamed parallel 
and the bolts turned to a driving fit. A washer not less than | 
in. thick shall be used under the nut. 

219. Riveting. Rivets shall look neat and finished with 
heads of approved shape, full and of equal size. They shall be 
centra] on shank and grip the assembled pieces firmly. Recup- 
ping and caulking will not be allowed. Loose, burned, or other- 
wise defective rivets shalJ be cut out and replaced. In cutting 
out rivets great care shall be taken not to injure the adjacent 
metal. If necessary they shall be drilled out. 

* This paragraph contains a Bpecial requirement which, bo be valid under 
these specifications, shall be specifically mentioned in (he contracl between 
the purchaser and the manufacturer. 



52 STANDARD SPECIFICATIONS 

220. Assembling. Riveted, members shall have all pans well 
pinned up and firmly drawn together with bolts before riveting 
is commenced. Contact surfaces to be painted. Par. 250.) 

22i. Web Plates. In buildings web plates of girders shall 
not be recessed from the backs of angles more than | in. 

In bridges web plates of girders which have no cover plates 
shall be flush with the backs of angles or shall, in the top chord, 
project above the same not more than | in. unless otherwise 
called for. 

When web plates are spliced not more than ^ in. clearance 
en ends of plates will be allowed. 

222. Splice Plates and Fillers. Web splice plates and fillers 
under stifTeners shall be cut to fit within J in. of flange angles. 

223. Web Stiffeners. StifTeners shall fit neatly between 
flanges of girders. Where tight fits are called for the ends : 
stiffeners shall be faced and shall be brought to a true contact 

og with the flange angles. 

224. Eye-Bars. Eye-bars shall be straight and true to size 
and shall be free from twists, folds in the neck or head, or any 
other defect. 

Heads shall be made by upsetting, rolling, or forging. Welding 
will not be allowed. The form of heads will be determined by 
the dies in use at the works where the eye-bars are made, if 
satisfactory to the engineer, but the manufacturer shall guarantee 
the bars to break in the body when tested to rupture. The 
thickness of head and neck shall not vary more than ^ in. 
from that specified. (Par. 24S.) 

225. Boring Eye-Bars. Before boring each eye-bar shall 
be properly annealed and carefully straightened. Pin holes 
shall be in the center line of bars and in the center of heads. 

- : same length shall be bored so accurately that, when 

placed together, pins ^ in. smaller in diameter than the pin 
holes can be passed through the holes at both ends of the bars 
at the same time without forcing. 

226. Pin Holes. Pin-holes shall be bored true to ga ug - 
smooth and straight: at right angles to the axis of the member 
and parallel to each other, unless otherwise called for. The 
boring shall be done after the member is riveted up. 

227. Variation in Pin Holes. The distance center to center 
of pin holes shall be correct within ^ in. and the diameter of 



MATERIALS AND WORKMANSHIP 53 

the holes not more than -J^ in. larger than that of the pin, for 
pins up to 5 in. diameter, and ^ in. for larger pins. 

228. Pins and Rollers. Pins and rollers shall be acurately 
turned to gauges and shal be straight and smooth and entirely 
free from flaws. 

229. Pilot Nuts. Pilot and driving nuts shall be furnished 
for each size of pin in such numbers as may be ordered. 

230. Screw Threads. Screw threads shall make tight fits 
in the nuts and shall be U.S. standard, except above the diameter 
of If in., when they shall be made with six threads per inch. 

231. Bed Plates. Expansion bed plates and vertical webs 
of pedestals shall be planed true and smooth. Cast wall or 
bed plates shall be planed top and bottom. The cut of the plan- 
ing tool shall correspond with the direction of expansion. 

232. Annealing. Steel, except in minor details, which has 
been partially heated shall be properly annealed. (Par. 233.) 

233. Steel Castings. All steel castings shall be annealed. 

234. Welds. Welds in steel will not be allowed. 

235. Shipping Details. Pins, nuts, bolts, rivets, and other 
small details shall be boxed or crated. 

236. Weight. The weight of every piece and box shall 
be marked on it in plain figures. 

237. Finished Weight. Payment for pound price contracts 
shall be by scale weight. No allowance over 2 per cent of the 
total weight of the structure, as computed from the plans, will 
be made for excess weight. 



PART VI 
INSPECTION, PAINTING, AND ERECTION 

Inspection and Testing 

238. Copies of Mill Orders. The purchaser shall be furnished 
copies of mill orders and no material shall be rolled, or work 
done, before the purchaser has been notified where the orders 
have been placed, so that he may arrange for the inspection. 

239. Facilities for Mill Inspection. The manufacturer shall 
furnish all facilities for inspecting and testing the weight and 
quality of all material at the mill where it is manufactured. 
He shall furnish a suitable testing machine for testing the spec- 
imens, as well as prepare the pieces for the machine, free of cost. 

240. Access to Mills. When an inspector is employed by 
the purchaser to inspect material at the mills, he shall have 
full access, at all times, to all parts of mills where material to 
be inspected by him is being manufactured. 

241. Facilities for Shop Inspection. The manufacturer shall 
furnish all facilities for inspecting and testing the weight and 
quality of workmanship at the shop where material is manu- 
factured. He shall furnish a suitable testing machine for testing 
full-sized members, if required. 

242. Starting Work in Shops. The purchaser shall be noti- 
fied well in advance of the start of the work in the shop in order 
that he may have an inspector on hand to inspect material and 
workmanship. 

243. Access to Shop. When an inspector is employed by 
the purchaser he shall have full access, at all times, to all parts 
of the shop where material under his inspection is being manu- 
factured. 

244. Accepting Material or Work. The inspector shall 
stamp each piece accepted with a private mark. Any piece 
not so marked may be rejected at any time and at any stage of 

54 



INSPECTION, PAINTING, AND ERECTION oo 

the work. If the inspector, through an oversight or otherwise, 
has accepted material or work which is defective or contrary 
to the specifications, this material, no matter in what stage of 
completion, may be rejected by the purchaser. 

245. Shop Plans. The purchaser shall be furnished complete 
shop plans. 

246. Shipping Invoices. Complete copies of shipping invoices 
shall be furnished to the purchaser with each shipment. 

247. Test to Prove Workmanship. Full-sized tests on eye- 
bars and similar members, to prove the workmanship, shall be 
made at the manufacturer's expense and shall be paid for by 
the purchaser at contract price if the tests are satisfactory. If 
the tests are not satisfactory the members represented by them 
will be rejected. 

248. Eye-Bar Tests. In eye-bar tests the fracture shall be 
silky, the elongation in 10 ft., including the fracture, shall not 
be less than 15 per cent; and the ultimate strength and true 
elastic limit shall be recorded. (Par. 224.) 

Painting 

249. Cleaning. Steelwork, before leaving the shop, shall 
be thoroughly cleaned and given one good coating of pure lin- 
seed oil, or such other paint as may be called for in the contract. 
well worked into all joints and open spaces. 

250. Contact Surfaces. In riveted work the surfaces com- 
ing in contact shall each be painted before being riveted together. 

251. Inaccessible Surfaces. Pieces and parts which are not 
accessible for painting after erection, including tops of stringers, 
eye-bar heads, ends of posts and chords, etc., shall have a good 
coat of paint before leaving the shop. 

252. Condition of Surfaces. Painting shall be done only 
when the surface of the metal is perfectly dry. It shall net 
be done in wet or freezing weather, unless protected under cover. 

253. Machine-Finished Surfaces. Machine-finished surfaces 
shall be coated with white lead and tallow before shipment or 
before being put ou1 into the open air. 

254. Painting Omitted. Hods, wires, hoops, etc., used 
for concrete reinforcement ami all other steelwork, or parts o( 

steelwork, entirely embedded in concrete shall not he painted. 



56 >T A N DA RDS PE( '1 FICATIO NS 

255. Painting after Erection. After the structure is erected 
the metal work shall be cleaned of scale, rust, and dirt, and then 
thoroughly and evenly painted. 

Steelwork in buildings, or where otherwise protected from 
exposure, shall have one additional coat of paint, mixed with 
pure linseed oil. or as specified by the Engineer. 

Steelwork in bridges, or other exposed structures, shall have 
two additional coats of paint as specified. 

The various coats of paint shall be of distinctly different 
shades or colors, and one coat must be allowed to dry before 
the next is applied. 

Erection 

256. When the Contractor Erects. Whenever the contractor 
is required to do the erection this requirement shall be specific- 
ally stated in the contract. 

The erection will then include the removal of any existing 
structure, all necessary hauling, the unloading of the materials 
and their proper care until the completion and acceptance of 
the work, as specified in Pars. 257 to 263. 

257. Removal of Old Structure. Whenever new structures 
are to replace existing ones the latter shall be carefully taken 
down, marked and scheduled to facditate re-erection, and removed 
by the contractor to some p^ce as specified in the contract. 

258. Interruption of Traffic. All operations shall be so con- 
ducted as not to impede or interrupt the work of other con- 
tractors, the traffic of any railroad, nor close any thoroughfare 
or waterway, nor conflict with any law, regulation, or ordinance 
of any properly constituted authority. 

259. Permits. Before commencing operations the contrac- 
tor shall, at his own expense, obtain all necessary permits and 
comply with their requirements. 

260. Erection. The contractor shall furnish, at his own 
expense, all necessary staging, falsework, materials, and tools, 
and shall erect the structure complete and paint the same. (Pars. 
254, 255.) 

In the case of a bridge, or trestle, he shall furnish and frame 
all floor timbers, guard rails, handrailings, trestle timbers, etc., 
complete ready for the rails. 

Wherever necessary he shall drill holes in the masonry, 



INSPECTION, PAINTING, AND ERECTION 57 

properly place all anchor bolts and securely attach them to the 
masonry by Portland cement, or otherwise. 

261. Safeguards and Damages. The contractor shall furnish, 
at his own expense, all watchmen, guards, signals, night lights, 
etc., for the prevention of accidents, and be responsible for the 
safety of the structure; and he shall assume full responsibility 
for all accidents to men, animals, and materials before the com- 
pletion and final acceptance of the structure and shall indemnify 
the purchaser for any and all claims for damages arising there- 
from. 

262. Defective Work. The contractor shall, at his own 
expense, remove, rebuild, or make good any damaged material 
or defective work, even if the same through an oversight or 
otherwise has been previously accepted. 

263. Clearing-up. When the erection is completed the con- 
tractor shall, at his own expense, remove all falsework, rubbish, 
and other useless material caused by his operations. 

264. When the Purchaser Erects. In case the purchaser 
erects the work the material shall be delivered on cars at the 
railway station mentioned in the contract. 

Any extra cost incurred by the purchaser, during the erection, 
due to defective material or workmanship, shall be borne by the 
contractor. 



PART VII 

STRUCTURAL TIMBER 

Quality 

265. Kinds of Timber. All timber for structures carrying- 
live loads shall preferably be of longleaf yellow pine, Douglas 
fir, white oak or western hemlock; for other structures short- 
leaf yellow pine, spruce, white pine or other equivalent good 
timber may be used. Chestnut and Norway pine may be used 
for piles. 

266. Quality of Timber. All timber must be cut within 
eighteen (18) months of the time of delivery, from sound trees 
and sawed to standard size. (Par. 267.) It must be close grained 
and solid, free from defects such as injurious ring shakes and 
crooked grain, unsound knots, knots in groups, decay, large 
pitch pockets, or other defects that will materially impair its 
strength or fitness for the purpose intended. (Pars. 269 to 274.) 

267. Size of Sawed Timber. All timber shall be sawed true, 
out of wind and shall, when dry, not measure scant in thickness 
more than the following: 

3^ in., for flooring and boards up to 1J in. thick, rough size; 
i in., for planking from If in. to of in. thick, rough size; 
and 

i in., for dimension timber from 6 in. thick and up, rough size. 

268. Dressing of Sawed Timber. When dressed timber over 
H in. in thickness is required the dimensions specified shall refer 
to rough sizes, unless otherwise mentioned. 

A reduction of not more than J in., beyond that specified 
in Par. 267 will be allowed for each planed surface. 

269. Shingles. Shingles shall be of pine, cedar, or cypress, 
as specified in the contract. They shall be from 16 to IS in. in 
length, from 4 to 6 in. wide, ^ in. in thickness at the tip and from 

5S 



STRUCTURAL TIMBER 59 

^ to J thick at the butt. They shall, in the first 10 in. from the 
butt, be absolutely free from sap, knots, or other defects. 

270. Piles. Timber piles shall preferably be of Southern 
(longleaf or shortleaf) yellow pine, white oak, Norway pine or 
cedar, as specified in the contract. 

They shall be cut from sound, live trees, shall be straight 
and free from wind-shakes, large knots, decay, and other impor- 
tant defects. The diameter of round piles near the butt shall not 
be less than 14 in. or more than 16 in., and at the tip, of piles 
under 40 ft. in length, not less than 8 in., or less than 6 in. in any 
case. 

They shall taper evenly from butt to tip and shall be so 
straight that a straight line, drawn from center to center of 
ends, shall at no point fall outside of the circumference. 

All piles shall be cut square at ends and they shall be stripped 
of their bark. (Par. 277.) 

271. Flooring. Flooring shall preferably be of rift shortleaf 
yellow pine or maple and shall be furnished in two grades (prime 
and common) and usually in lengths between 4 and 16 ft. and 
not over 2^-in. face. The thickness of flooring shall be under- 
stood to be the thickness of the finished material after dressing. 

The exact kind of wood, grade, width, and thickness shall be 
specified in the contract. 

(a) Prime Flooring. Prime flooring shall be edge grained. 

kiln dried, matched, tongued and grooved, well manu- 
factured so as to be free from planer's marks, edge 
splinters, grain slivers, etc. It shall show one face 
all heart and shall be free from knots, shakes, sap, and 
pitch pockets. 

(b) Common Flooring. Common flooring shall be like prime 

flooring except that the material may show one knot. 
not over 1 in. in diameter, to every I ft. in length, also 
unimportant pitch streaks and sap stains. 

272. Ceiling and Wainscoting. Ceiling and wainscoting shall 
be graded as the flooring, bu1 shall in addition l>e double beaded 
and very carefully dressed. 

273. Planks and Scantling. Planks and scantling, when 
used for floors, struts, cross and sway bracing, shall show one 
face all heart, the other lace and two sides shall show not less 
than 7.~> per cent heart, measured across the face or sides any- 



60 



;tandard specifications 



where in the piece. It shall be free from knots H in. in diameter 
and over. 

When used for other purposes it shall be square edged, free 
from knots 2^ in. in diameter and over, and wanes not extend- 
ing over 5 per cent of the surface area may be allowed in 5 per 
cent of the total number of pieces in any one size. 

274. Dimension Timber. Dimension timber, when used as 
beams, bridge joists, or stringers, caps, and sills in trestles and 
posts, shall show not less than 75 per cent heart on each of the 
four sides, measured across each side anywhere in the length 
of the piece. Xo loose knots, or knots greater than 2^ in. in 
diameter or over one-quarter (J) the width of the face of the 
stick in which they occur, will be allowed. Knots must not be in 
groups, or be located within 3 in. of the edges. 

When used for other purposes it shall be square edged, except 
it may have 1 in. wane on one comer and ring shakes must not 
extend over one-eighth J) of the length of the piece. 



I nit Stresses 

275. Timber in Buildings and Highway Bridges. The 
maximum stresses due to the combined effect of dead. snow, 
wind, and live loads, including bending and impact, if any. shall 
not exceed the following values in pounds per square inch: 





Bend- 
ing 
Ex- 
treme 
Fibers. 


Ten 


don 


Compression. 


Shearing. 


Timber. 


With 
Grain. 


Across 
Grain. 


With 
Grain. 


Under 

1 r- 

Diam. Gram 


With 
Grain. 


Across 
Grain. 


Douslas fir 


1100 


1000 




1200 


900 300 


160 


SOO 


Hemlock, western 


1000 


- 




1000 


750 200 


150 


700 


Oak. white 


1000 


1000 


200 


1300 


975 450 


160 


1000 


Pine, white 


soo 


9 


50 


1000 


750 150 


100 


600 


yellow, longleaf . 


1200 


1200 


60 


1300 


075 ' 260 


180 


1200 


short leaf . 


1000 




50 


1100 


S25 ISO 


170 


1000 


Spruce 


900 


800 


50 


1100 


n25 ISO 


100 


600 



For columns whose length does not exceed lod the above 
values, given for "'Compression under 15 diameters." may be 
used. 



STRUCTURAL TIMBER 



61 



When the length of the column exceeds lod the above values, 
given for "Compression with grain/' shall be reduced as follows: 



S = c- 



cl 
60d ; 



where S= allowable working stress per square inch 
c= u compression with grain " given above; 
1 = unsupported length of column in inches; 
d = least width of column in inches; 



and maximum 



-45. 



276. Timber in Railroad Bridges and Trestles. The max- 
imum stresses due to the combined effect of dead and live loads, 
lateral and longitudinal forces, including bending and impact, 
shall not exceed the following values in pounds per square 
inch. 



Timber. 



Bend- 
ing Ex- 
treme 
Fibers. 


Tension. 


Compression. 


With 
Grain. 


Across 
Grain. 


With 
Grain. 


Under 

15 
Diam. 


Across 
Grain. 


1800 


1600 




2000 


1400 


500 


1600 


1300 




1600 


1120 


320 


1600 


1600 


325 


2100 


1470 


750 


1300 


1300 


80 


1600 


1120 


250 


2000 


2000 


100 


2100 


1470 


430 


1600 


1500 


80 


1800 


L260 


300 


1500 


1300 


80 


ISO!) 


1260 


300 



Shearing, 



With 
Grain. 



Across 
Grain. 



Douglas fir 

Hemlock, western . . . 

Oak, white 

Pine, white 

' ' yellow, longleaf 

' ' shortleaf 

Spruce 



260 
250 
260 
160 
300 
280 
L60 



L300 

1150 

L600 

1000 

2000 

1000 
1000 



For columns whose length does not exceed 1,V the above 
values, given for "Compression under 15 diameters," may be 
used. 

When the length of the column exceeds 15</ the above values, 
given for "Compression with grain," shall be reduced as follows: 



rjl 



62 STANDARD SPECIFICATIONS 

where S = allowable working stress per square inch; 
ci = " compression with grain " given above; 
/ = unsupported length of column in inches; 
d= least width of column in inches; 

and maximum -r = 35. 

a 

277. Piles. The maximum load per pile due to the combined 
effect of dead and live loads, lateral and longitudinal forces, 
including impact, if any, shall not exceed the following: 

„ 2.5WH 



where P — allowable pressure in pounds per pile, limited as per 
below ; 
W= weight of drop hammer in pounds; 
H = height of drop in feet; 

s = average sinking in inches due to the last five blows 
when squarely struck. 

When the piles are driven through wet and loose soil to a good 
bearing the pressure shall not exceed 300 lbs. per sq.in. of their 
average cross-section. When driven through a firm soil this 
pressure may be increased to 600 lbs. (Par. 270.) 

Details of Design 

278. Flooring and Joists (Buildings). Floor planks and 
floor joists in buildings, carrying plastering, shall be proportioned 
with regard to their stiffness, limiting their deflection to one-three- 
hundred-and-sixtieth (-^J-g-) of the span. 

All other timber in buildings may be proportioned with 
regard to its strength. 

279. Flooring (Highway Bridges). Floor planks for the 
roadway, when a single thickness is used shall have a minimum 
thickness of 3 in., shall be laid with J-in. open spaces and shall 
be securely spiked to the joists. 

Footwalk planks shall have a minimum thickness of 2 in., 
shall be at least 6 in. wide and shall be spaced with +-in. openings. 

Where an additional wearing surface is being used, the min- 
imum thickness of which shall be 1^ in., the thickness of the 



STRUCTURAL TIMBER 63 

supporting plank may be reduced to 2\ in., in which case the 
latter shall be laid diagonally with ^-in. openings. 

All floor planks shall be laid with the heart side down. 

280. Joists (Highway Bridges). The minimum size of 
joists shall be 3" X12". They shall be notched over their bear- 
ings at least \ in., bringing the top surfaces to exact level. Where 
they rest on top of the floor beams the intermediate joists shall 
lap by each other over the full width of same, with \ in. open 
space for circulation of air, whereas the outside joists shall have 
their outer faces flush from end to end of span. 

If the floor plank be continuous each joist may be assumed 
to carry only two-thirds (f) of the concentrated load. 

The maximum spacing for wooden joists shall be 2 ft. 6 in. 

281. Wheel Guards (Highway Bridges). There shall be a 
wheel-guard on each side of the roadway having a minimum 
size of 4"X6", laid on flat, and blocked up on shims 2"X6 // 
and 12 in. long. The shims shall have a maximum spacing of 5 
ft. from center to center. The wheel guards shall be spliced with 
half-and-half joints 6 in. long over a shim and shall be fastened 
to the joist beneath with a three.-quarter (}) in. bolt passing 
through the center of each shim. 

282. Handrailing (Highway Bridges). The posts shall be 
6"X4", spaced not more than 5 ft. apart, and shall be firmly 
fastened. There shall be two lines of railing of 2 r/ X6" plank, 
the upper line of which shall be placed on flat and the lower 
one on edge. 

283. Cross Ties (Railroad Bridges). The cross tics shall be 
of such size as to give the requisite resistance to bending, under 
the assumption that the maximum load is distributed equally 
over three ties and that the impact equals 100 per cent. 

Every tie shall be notched down not less than \ in. and be 
brought to a full and even bearing upon the stringers, and every 
third tie shall be secured thereto by a |-in. hook bolt. 

The minimum sizes of cross tics shall be: 

(a) For electric railroads 6"X8"X 8' (laid on flat); and, 

(6) For steam railroads 8"X8"X10'. 
The tics shall be spaced 1 1 in. center to center, with a her open- 
ing of not more than 6 in., or less than I in. 

On curves the super-elevation of the outer rail shall be obtained 

by using beveled ties. 



64 



STANDARD SPECIFICATIONS 



284. Guard Rails (Railroad Bridges). The minimum size of 
the outer guard rails shall be 6"X8" (laid on flat) and so placed 
that their inner faces are not less than 3 ft. 3 in., or more than 
3 ft. 6 in., from center of track. 

The minimum size of the inner guard rails shall be 6"X8" 
(laid on flat) and so placed that their outer faces are not less 
than 1 ft. 11 in., or more than 2 ft. from center of track. 

All guard rails shall be continuous over piers and abutments; 
they shall be spliced with half-and-half joints over a tie, shall be 
notched 1 in. over every tie and shall be fastened to every third 
tie and through the splice by a three-quarter (J) in. bolt. The 
floor system shall be fastened to the supporting girders by a 
three-quarter (f) in. hook bolt through every third tie. 

All heads or nuts of bolts on the upper faces of guard rails 
shall be countersunk into the wood and placed in a cup washer. 

285. Pile Trestles. For heights less than 30 ft. pile trestles 
may be used, and their spacing, center to center of bents, shall 
not exceed 15 ft. Each bent whose height exceeds 10 ft. shall 
be braced transversely and, if it exceeds 15 ft., shall in addition 
be braced longitudinally in at least every fifth panel. 

286. Framed Trestles. For trestles of greater height than 
30 ft. framed bents shall be used. They shall be supported upon 
foundations of concrete piers, timber sills, or piles. All framed 
bents shall be braced transversely and, in every alternate panel, 
longitudinally. 

287. Trestle Stringers. Wherever there are several timber 
stringers under each rail they shall be placed symmetrically 
under same. The stringers shall break joints over the bents, 
shall be securely fastened thereto, and shall be separated from 
each other by means of cast-iron fillers one-half (J) in. thick 
spaced not over 5 ft. apart. 



PART VIII 

CEMENT 

The following specifications for cement were adopted August 
15, 1908, as standard by the American Society for Testing 
Materials. 

General Observations 

288. (a) These remarks (Pars. 288-293) have been prepared 
with a view of pointing out the pertinent features of the various 
requirements and the precautions to be observed in the inter- 
pretation of the results of the tests. 

(6) The committee would suggest that the acceptance or 
rejection under these specifications be based on tests made by an 
experienced person having the proper means for making the 
tests. 

289. Specific Gravity. Specific gravity is useful in detecting- 
adulterations. The results of tests of specific gravity are not 
necessarily conclusive as an indication of the quality of a cement, 
but when in combination with the results of other tests may 
afford valuable indications. 

290. Fineness. The sieves should be kept thoroughly dry. 

291. Time of Setting. Great care should be exercised to 
maintain the test pieces under as uniform conditions as possible. 
A sudden change or wide range of temperature in the room in 
which the tests are made, a very dry or humid atmosphere, and 
other irregularities, vitally affect the rate of setting. 

292. Tensile Strength. Each consumer must !i\ the minimum 
requirements for tensile strength to suit his own conditions. The} 
shall, however, be within the limits stated. 

293. Constancy of Volume : 

(a) The tests for constancy of volume are divided into i\\<> 
classes, the first normal, the second accelerated. The 
latter should he regarded as a precautionary tesl only, 
and not inf all able. So many conditions enter into the 

65 



STANDARD SPECIFICATIONS 

making and interpreting of it that it should be used 
■with extreme care. 

(b) In making the pats the greatest care should be exercised 

to avoid initial strains due to molding or to too rapid 
drying-out during the first twenty-four hours. The 
pats should be preserved under the most uniform 
conditions possible, and rapid changes of temperature 
should be avoided. 

(c) The failure to meet the requirements of the accelerated 

tests need not be sufficient cause for rejection. The 
ment may. however, be held for twenty-eight days 
and a retest made at the end of that period, using a new 
sample. Failure to meet the requirements at this time 
should be considered sufficient cause for rejection, 
although in the present state of our knowledge it can- 
not be said that such failure necessarily indicates un- 
soundness, nor can the cement be considered entirely 
- isfactory simply because it passes the tests 

Speoticati 2fS 

294. General Conditions : 

(a) All cement shall be inspected. 

(6) Cement may be inspected either at the place of manu- 
facture or on the work. 

(c) In order to allow ample time for inspection and testing, 
the cement should be stored in a suitable weather-tight 
building having the floor properly blocked or raised 
from the ground. 

{d). The cement shall be stored in such a manner at to permit 
iss for proper inspection and identification of 
each shipment. 

(e) Every facility shall be provided by the contractor and 
a period of at least twelve days allowed for the inspec- 
tion and necessary tests 

(J) Cement shall be delivered in suitable packages with the 
brand and name of manufacturer plainly marked thereon. 

(g) A bag of cement shall contain 9-± lbs. of cement net. 

Each barrel of Portland cement shall contain 4 bags 
and each barrel of natural cement shall contain 3 I gs 
of the above net weight. 



CEMENT 67 

(h) Cement failing to meet the 7-day requirements may be 
held awaiting the results of the 28-day tests before 
rejection. 

(i) All tests shall be made in accordance with the methods 
" proposed by the Committee on Uniform Tests of Cement 
of the American Society of Civil Engineers, presented 
to the Society, January 21, 1903, and amended January 
20, 1904, and January 15, 1908, with all subsequent 
amendments thereto. 

(/) The acceptance or rejection shall be based on the following 
requirements:. (Pars. 295 to 306.) 

Natural Cement 

295. Definition. This term shall be applied to the finely 
pulverized product resulting from the calcination of an argil- 
laceous limestone at a temperature only sufficient to drive off the 
carbonic acid gas. 

296. Fineness. It shall leave by weight a residue of not 
more than 10 per cent on the No. 100, and 30 per cent on the No. 
200 sieve. 

297. Time of Setting. It shall not develop initial set in less 
than 10 minutes, and shall not develop hard set in less than 
30 minutes, or in more than 3 hours. 

298. Tensile Strength. The minimum requirements for ten- 
site strength for briquettes 1 in. square in cross-section shall be 
within the following limits, and shall show no retrogression in 
strength within the periods specified:* 

NEAT CEMENT 
Age. Strength. 

24 hours in moist air 50 100 lbs. 

7 days (1 day in moist air, 6 days in water) 100 200 ' 

28 days (1 " " 27 " " ) 200 300 " 

ONE PART CEMENT, THREE PARTS STANDARD SAND 

7 days (1 day in moist air, (> days in water) 25 75 lbs. 

28 <lays (I " " 27 " " ) .. 75-150 " 

* For example, the minimum requirement for the 24-hour neat cement 
test should be some specified value within the limits of 50 and LOO lbs., and so 
on for each period stated. 






6^ STANDARD SPECIFICATIONS 

If the minimum strength is not specified, the mean of the above 
values shall be taken as the minimum strength required. 

299. Constancy of Volume. Pats of neat cement about 3-in. 
in diameter, J-in. thick at center, tapering to a thin edge, shall 
be kept in moist air for a period of 24 hours. 

(a) A pat is then kept in air at normal temperature. 

(6) Another is kept in water maintained as near 70°, F. as 

practicable. 
(c) These pats are observed at intervals for a least 28 days, 

and, to satisfactorily pass these tests, should remain 

firm and hard and show no signs of distortion, checking, 

cracking, or disintegrating. 

Portland Cement 

300. Definition. This term applies to the finely pulverized 
product resulting from the calcination to incipient fusion of an 
intimate mixture of properly proportioned argillaceous and cal- 
careous materials, and to which no addition greater than 3 per 
cent, has been made subsequent to calcination. 

301. Specific Gravity. The specific gravity of the cement, 
ignited to a low red heat, shall be not less than 3.10. and the 
cement shall not show a loss on ignition of more than 4 per cent. 

302. Fineness. It shall leave by weight a residue of not 
more than 8 per cent on the Xo. 100, and not more than 25 per 
cent on the Xo. 200 sieve. 

303. Time of Setting. It shall not develop initial set in less 
than 30 minutes, and must develop hard set in not less than 1 
hour, nor more than 10 hours. 

304. Tensile Strength. The minimum requirements for 
tensile strength for briquettes 1 in. square 111 section shall be 
within the periods specified.* 



NEAT CEMENT 
Age. - Strength. 

24 hours in moist air 150-200 lbs. 

7 days (1 day in moist air, 6 days in water) 450-550 " 

28 days (1 '■' " 27 " " ) 550-650 " 

* For example, the minimum requirement for the 24-hour neat cement 
test should be some specified value within the limits of 150 and 200 lbs., 
and so on for each period stated. 






CEMENT 69 

ONE PART CEMENT, THREE PARTS STANDARD SAND 

7 days (1 day in moist air, 6 days in water) 150-200 lbs. 

28 days (1 " " 27 " " ) 200-300" 

If the minimum strength is not specified, the mean of the above 
values shall be taken as the minimum strength required. 

305. Constancy of Volume. Pats of neat cement about 
3 in. in diameter, \ in. thick at center, and tapering to a thin 
edge, shall be kept in moist air for a period of 24 hours. 

(a) A pat is then kept in air at normal temperature and 
observed at intervals for at least 28 days. 

(6) Another pat is kept in water maintained as near 70° F. 
as practicable, and observed at intervals for at least 
28 days. 

(c) A third pat is exposed in any convenient way in an 

atmosphere of steam, above boiling water, in a loosely 
closed vessel for 5 hours. 

(d) These pats, to satisfactorily pass the requirements, shall 

remain firm and hard and show no signs of distortion, 
checking, cracking, or disintegrating. 

306. Sulphuric Acid and Magnesia. The cement shall not 
contain more than 1.75 per cent of anhydrous sulphuric 
acid (SO3), nor more than 4 per cent of magnesia (MgO). 



PART IX 

PORTLAND-CEMENT CONCRETE 



The following specifications for Portland-cement concrete 
were adopted in 1904, as standard by the American Railway 
Engineering and Maintenance of Way Association, see Pro- 
ceedings, Vol. V. 

307. Cement. The cement shall be Portland, either American 
or foreign, which will meet the requirements of the standard 
specifications adopted by the American Society for Testing 
Materials. (See Part VIII.) 

308. Sand. The sand shall be clean, sharp, coarse, and of 
grains varying in size. It shall be free from sticks and other 
foreign matter, but it may contain clay or loam not to exceed 
5 per cent. Crusher dust, screened to reject all particles over 
^ in. in diameter, may be used instead of sand, if approved by 
the Engineer. 

309. Stone. The stone shall be sound, hard, and durable, 
crushed to sizes not exceeding 2 in. in any direction. For rein- 
forced concrete, the sizes usually are not to exceed f in. in any 
direction, but may be varied to suit the character of the rein- 
forcing material. 

310. Gravel. The gravel shall be composed of clean pebbles 
of hard and durable stones of sizes not exceeding 2 in. in diam- 
eter, free from clay and other impurities except sand. When 
containing sand in any considerable quantity, the amount 
per unit of volume of gravel shall be determined accurately to 
admit of the proper proportion of sand being, maintained in the 
concrete mixture. 

311. Water. The water shall be clean and reasonably 
clear, free from sulphuric acid and strong alkalies. 

312. Mixing by Hand : 

(a) Tight platforms shall be provided of sufficient size to 
accommodate men and materials for the progressive 

70 



PORTLAND-CEMENT CONCRETE 71 

and rapid mixing of at least two batches of concrete 
at the same time. Batches shall not exceed 1 cubic 
yard each, and smaller batches are preferable, based 
upon a multiple of the number of sacks to the barrel. 

(b) Spread the sand evenly upon the platform, then the 

cement upon the sand, and mix thoroughly until of 
an even color. Add all the water necessary to make 
a thin mortar, and spread again; add the gravel if used, 
and finally the broken stone, both of which, if dry, 
should first be thoroughly wet down. Turn the mass 
with shovels or hoes until thoroughly incorporated, 
and until all the gravel and stone is covered with mor- 
tar, which will probably require the mass to be turned 
four times. 

(c) Another method, which may be permitted at the option 

of the engineer in charge, is to spread the sand, then 
the cement, and mix dry; then the gravel or broken 
stone, add water, and mix thoroughly as above. 

313. Mixing by Machine. A machine mixer shall be used 
wherever the voiume of work will justify the expense of installing 
the plant. The necessary requirements for the machine shall 
be that a precise and regular proportioning of materials can be 
controlled, and the product as delivered shall be of the required 
consistency and be thoroughly mixed. 

314. Consistency. The concrete shall be of such consistency 
that when dumped in place it will not require much tamping. 
It shall be spaded down, and be tamped sufficiently to level it 
off, after which the water should rise freely to the surface. 

315. Forms: 

(a) Forms shall be well built, substantial and unyielding, 
properly braced or tied together by means of wire or 
rods, and shall conform to the lines given. 

(6) For all important work, the lumber used for face work 
shall be dressed on one side and both edges, and shall 
be sound and free from loose knots, secured to the 
studding or uprights in horizontal lines. 

(c) For backing and other rough work, undressed lumber 

may be used. 

(d) Where corners of the masonry and other projections 

liable to injury occur, suitable moldings shall be 



72 STANDARD SPECIFICATIONS 

placed in the angles of the forms to round or bevel 
them off. 

(e) Lumber once used in forms shall be cleaned before being 
used again. 

(/) The forms must not be removed within 36 hours 
after all the concrete in that section has been placed. 
In freezing weather, they must remain until the con- 
crete has had sufficient time to become thoroughly 
hardened. 

(g) In dry but not freezing weather, the forms shall be drenched 
with water before the concrete is placed against them. 

316. Depositing: 

Each layer should be left somewhat rough to insure bond- 
ing with the next layer above; and. if the concrete 
has already set. it shall be thoroughly cleaned by scrub- 
bing with coarse brushes and water before the next 
layer is placed upon it. 
(6) Concrete shall be deposited in the molds in layers of such 
thickness and position as shall be specified by the 
Engineer in charge. Temporary planking shall be 
placed at the ends of partial layers, so that none shall 
run out to a thin edge. In general, excepting in arch 
work, all concrete must be deposited in horizontal 
layers of uniform thickness throughout. 

(c) The work shall be carried up in sections of convenient 

length and the sections shall be completed without 
intermission. 

(d) In no case shall work on a section stop within IS in. of 

the top. 

(e) Concrete shall be placed immediately after mixing, and 

any having an initial set shall be rejected. 

317. Expansion Joints: 

(a) In exposed work, expansion joints may be provided at 
intervals of 30 to 100 ft., as the character of the struc- 
ture may require. 
A temporary vertical form or partition of plank shall be 
set up. and the section behind shall be completed as 
though it were the end of the structure. The partition 
shall be removed when the next section is begun, and 
the new concrete shall be placed against the old without 






PORTLAND-CEMENT CONCRETE 



73 



mortar flushing. Locks shall be provided, if directed 
or called for by the plans, 
(c) In reinforced concrete the length of these sections may be 
materially increased at the option of the Engineer. 

318. Facing: 

(a) The facing may be made by carefully working the coarse 
stone back from the form by means of a shovel, bar, or 
similar tool, so as to bring the excess mortar of the con- 
crete to the face. 
Or, 

(6) About 1 in. of mortar (not grout) of the same pro- 
portion as used in the concrete may be placed next to 
the forms immediately in advance of the concrete, in 
order to secure a perfect face. 

(c) Care must be taken to remove from the inside of the 
forms any dry mortar in order to secure a perfect face. 

319. Proportions. The proportions of the materials in the 
concrete shall be as specifically called for by contract, or as set 
forth herein, upon the lines left for that purpose, the volume of 
cement to be based upon the actual cubic contents of 1 barrel 
of specified weight. 



Structure 



Parts by Volume 



Cement. 



Sand. 



Gravel. Broken Stone. 



320. Finishing: 

(a) After the forms arc removed, which should generally be 
as soon as possible after the concrete is sufficiently 
hardened, any small cavities or openings in the face 
shall be neatly filled with mortar, if necessary in the 
opinion of the Engineer. Any ridges dm* to cracks 
or joints in the lumber shall be rubbed down with chisel 
or wooden float. The entire face may then be washed 
with a thin grout of the consistency of whitewash. 



71 - XDARD 8PECIFICATK 3 

mixed in the same proportion as the mortar of the 
concrete. The wash shall be applied with a brush. 
The earlier the above operations are performed the 
better will be the result. 
(b) The tops of bridge seats, pedestals, copings, wing walls. 
etc.. when not finished with natural stone coping, shall 
be finished with a smooth surface composed of one part 
cement to two parts of granite or other suitable screen- 
ings or sand, applied in a layer J to 1 in. thick. This 
must be put in place with the last course of concrete. 

321. Waterproofing. Where waterproofing is require 
thin coat of mortar or grout shall be applied for a finishing coat, 
upon which shall be placed a covering of suitable waterproofing 

rial. 

322. Freezing Weather. Ordinarily concrete to be left al 
the surface of the ground shall not be constructed in freezing 
weather. Portland-cement concrete may be built under these 
conditions by special instructions. In this case the sand, water. 
and broken stone shall be heated: and in severe cold, salt shall 

ided in the proportion of about 2 lbs. per cubic yard. 

323. Reinforced Concrete. See Part X. 



PART X 

REINFORCED CONCRETE 

General Requirements 

324. Preparation of Plans. All plans shall be prepared, and 
drawn to a scale sufficiently large so as to show clearly the quan- 
tity and the exact position of all reinforcement; the method of its 
anchorage, where continuity or extra bonding are required; and 
in short all details of parts affecting strength or appearance. 

325. Adherence to Plans. The contractor shall, during 
construction, adhere strictly to the plans, as the strength of the 
finished structure depends upon this; and the inspector shall 
not be allowed to make any changes therein without the written 
authority of the engineer. 

326. Placing of Forms: 

(a) The falsework and forms shall be substantial and unyield- 
ing, properly braced or tied together by means of wire 
or rods, and shall be so designed that the concrete will 
conform to the proper dimensions and contours. 

(6) The timber used shall not be too dry, as a free absorption 
of moisture will cause swelling and consequent deform- 
ation of the concrete; it shall be planed smooth on 
both edges and one side, shall be covered with a coating 
of oil, soap, limewash or other substance to prevent the 
concrete from adhering to the surface, and shall have 
all joints closed so as to prevent the leakage o\' grout. 

(r) In general the forms shall be simple of construction, easy 
of erection, maintenance, and removal, and they shall 
frequently be inspected during the progress of the work 
that perfect alignment may be maintained. 

(d) All forms having been previously used shall be thoroughly 
cleansed and prepared before being used again. 

327. Metal Reinforcement. No metal reinforcemcnl used 
in concrete shall be painted, hut shall be free from dirt, oil. or 



76 STANDARD SPECIFICATIONS 

grease. All mil] scale shall be removed by hammering the metal, 
or preferably by pickling the same in a weak solution of muriatic 
acid. 

328. Placing of Reinforcement. The metal reinforcement 
shall be placed and kept during the deposition and tamping of 
the concrete in the proper position. Whenever it is practicable 
it shall be placed in position first. This can usually be done 
where the metal occurs in the bottom of the forms, by supporting- 
it on transverse wires or otherwise. 

329. Ingredients. The contract covering any reinforced 
concrete work shall specifically state the quality of the cement 
and the aggregates and, if possible, the particular brands of 
cement, sand, gravel, or broken stone to be used; shall state the 
exact proportions of cement and aggregates and the approxi- 
mate proportion of water to be mixed, and the required strength 
in compression to be attained in 28 days by test cylinders S 
in. in diameter and 16 in. long. 

Methods of measurements of the proportions of the various 
ingredients, including the water, shall be used, which will secure 
separate uniform measurements at all times, preferably by 
weight . 

330. Mixing by Hand. (See Par. 312.) 

331. Mixing by Machine. (See Par. 313.) 

332. Consistency. The materials should be mixed wet 
enough to produce a concrete of such a consistency as will flow 
into the forms and about the metal reinforcement, and, at the 
same time, can be conveyed from the mixer to the forms without 
separation of the coarse aggregates from the mortar. 

333. Placing of Concrete: 

(a) Before placing the concrete care shall be taken to see 

that the forms are thoroughly wetted and the space 
to be occupied by the concrete is free from debris. 

(b) Great care must also be taken to insure the coating of 

the metal with cement mortar and the thorough flushing 
of the bottoms of the forms with same; after which the 
concrete must be deposited rapidly, thoroughly com- 
pacting it around the metal. 

(c) Concrete, after the addition of water to the mix, shall 

be handled rapidly, in as small masses as is practicable, 
from the place of mixing to the place of final deposit. 



REINFORCED CONCRETE 77 

(d) No concrete having an initial set shall be used, nor shall 

the retempering of mortar or concrete (i.e., remixing 
with water after it has partially set) be permitted. 

(e) Where the metal reinforcement occurs in several layers 

the concrete shall be deposited in equal layers and 
rammed separately. Otherwise the concrete shall be 
spread in horizontal layers not exceeding 4 in. in 
slabs, or 6 in. in any case. 
{/) The concrete shall be deposited in a manner that will 
permit the most thorough compacting, such as can 
be obtained by working with a straight shovel or slic- 
ing tool kept moving up and down till all the ingredients 
have settled in their proper place by gravity and the 
surplus water is forced to the surface. 
(g) In columns having circumferential reinforcement the 
concrete shall preferably be introduced by means of a 
tremie or tube, in order to prevent the ingredients 
from sorting in layers. To prevent settlement or 
shrinkage in freshly made columns a period of at least 
two hours shall elapse before any girder or beam over 
them may be commenced. 
(h) In depositing concrete under water special care shall 
be exercised to prevent the cement from floating away 
and to prevent the formation of laitance; when laitance 
has formed it shall be removed before placing fresh 
concrete. 
(i) When work is resumed concrete previously placed shall 
be roughened, thoroughly cleansed of foreign material 
and laitance, drenched and slushed with a mortar 
consisting of 1 part Portland cement and 2 pa its 
sand. 
(/) The faces of concrete exposed to premature drying should 
be kept wet for a period of at least 7 days after 
molding. 
334. Freezing Weather. Concrete for reinforced structures 
shall not be mixed or deposited at a freezing temperature, excepl 
under special instruction. In this case the Band, water, and 
broken stone shall he heated, hut no salt shall he added. 

Effective means shall he provided to prevenl the concrete 
from freezing until it has thoroughly hardened. 



7^ STANDARD SPECIFICATIONS 

335. Removal of Forms: 

(a) The t«me for removal of forms and shores, being an 
extremely important consideration, shall be determined 
in each case by the engineer after inspection. As a 
guide the following important determinants are men- 
tioned: size of structure and general dimensions of parts; 
methods of mixing and proportions of mixture; whether 
slow or quick-setting cements are used: atmospheric 
conditions: importance of live loading and its ratio 
to the dead load; length of period between the removal 
of forms and shores and the time when the maximum 
loading may be attained, etc. But in any case the 
supporting shores shall be left in place until their re- 
moval is permitted by the engineer. 
(6) The minimum time for the removal of Forms (not the 
supporting shores shall be as follows: 

For Bottom of Slabs 4 days, for spans of 4 ft. or less, plus 
1 day extra for each additional foot of span. 

For (Sides and Beams and Girders 7 days. 

For Columns 4 days. 

For Bridge Arches 28 days. 
(c) The minimum time for the removal of Shores shall be as 
follows : 

For Bottoms of Beams and Girders 21 days, for spans of 
10 ft. or less, plus one-half {h) day for each additional 
foot of span. 

The original shores must in no case be taken down, replaced 

or disturbed, until permitted by the Engineer. 

((/) When frosty weather occurs during the above periods an 

extension of time shall be made equal to its duration. 

(e) During the setting and before the removal of. forms no 

extraneous loading shall be placed upon the concrete. 

The forms shall be removed with care so as not to deface 

the structure or to disturb the remaining supports. 

Loads 

336. Dead Load. The dead load consists of: 

(a) The weight of the reinforced concrete, which shall be 
taken at 150 lbs. per cubic foot. 






REINFORCED CONCRETE 79 

(b) The weight of the roof covering, flooring, paving, or -ballast, 

if any. (For weight of same see Pars. 3, 4, 5, 59, 109.) 

(c) The weight of railway tracks, if any. (For weights of 

same see Pars. 59, 109.) 

(d) The snow load, if any. (For weight of same see Par. 6.) 

337. Wind Pressure or Lateral Forces. (See Pars. 7, 62, 113, 
114.) 

338. Centrifugal Forces. (See pars. 63, 116.) . 

339. Traction Forces. (See Pars. 64, 115.) 

340. Live Loads. (See Pars. 9, 10, 60, 110, 111.) 

341. Impact. An impact allowance shall be added to the 
computed maximum live-load stresses, as follows: 

(a) For floors of schools, theaters, ] , .,_ x 

. 1 / 100 \ 

churches, armories, dancing or \ Impact = #S( y qnft ) . 

other public halls and factories .... J 

(b) For floors carrying moving machinery 1 , , 

for crane girders and posts; for j- Impact = S I j ~ J . 
highway bridges J 

(c) For railroad bridges Impact = S I T ) . 

where S = computed maximum live-load stress, moment or shear, 
L = length of span in feet, or loaded length of span, which- 
ever gives a maximum. 

No impact allowance shall be added to stresses produced by 
traction, centrifugal, and lateral or wind forces. 

Calculation of Stresses 

342. General Dimensions. The following dimensions shall 
first be calculated or assumed: 

Span of slabs, supported at ends, clear opening plus thick- 
ness of slab. 

Span of slabs, continuous, c. to c. of beams. 

Span of beams and girders, c. to c. of support. 

Length of columns, the maximum unsupported length. 

343. Assumptions: 

(a) The ratio of the modulus of elasticity of steel (E a ) k to 
the modulus of elasticity of concrete (E c ) shall be taken 
at 15, or /<:,. : /•:, lf>. 



so 



STANDARD SPECIFICATIONS 



(6) The modulus of elasticity of concrete in compression 
is constant, and the relation of stress to strain in con- 
crete is rectilinear. 

(c) In calculating the moment of resistance of slabs, beams, 
or girders the tensile value of the concrete shall be 
neglected. 

344. Bending Moments. The bending moments shall be 
computed as follows: 

(a) For slabs, reinforced in one direction only, 

When supported at both ends,M= 1.5wL 2 , at center 

= at ends 

When supported at one end, 1 , r . _ TO 

. X1 fl ' \M=1.2wL 2 , at center 

continuous at other J 

f at one end 

~~ l-1.2wL 2 attheother. 

When continuous, or fixed ]M = wL 2 , at center, 

at both ends, J = — wL 2 at ends, 

where M= bending moment in inch-pounds; 

w = dead or live load in pounds per linear foot, uniformly 

distributed ; 
L = length of span in feet. (Par. 342.) 

(6) For slabs whose length does not exceed 1^ times their 
width and which are reinforced in both directions, 
the loading shall be assumed to be divided between the 
transverse and the longitudinal systems, as follows: 



Ratio of long to short side 


1 


1.1 


1.15 


1.2 


1.25 






Proportion of loading carried by trans- 
verse svstem 


0.50 
0.50 


0.59 
0.41 


0.64 
0.36 


0.67 
0.33 


0.71 


Do. by longitudinal system 


0.29 



and shall be distributed to the supporting beams in a 
variable ratio, increasing toward the center as the 
ordinates of a triangle, 
(c) For beams and girders the bending moments shall, aside 
from loading, depend upon the end conditions, as given 
above, under (a). 



REINFORCED CONCRETE 81 

(d) For slabs or beams, continuous over two spans only, or 
for concentrated loads, or other unusual conditions, 
the moments and shears shall be obtained by the 
" Theorem of Three Moments.' 7 

345. Resisting Moments : 

(a) In any slab, beam, or girder reinforced for compression 
the resisting moment of the steel in compression shall 
equal the compressive value of concrete X 15 X its lever 
arm. (Par. 3486.) 
(6) In T-beams, where adequate bond between slab and web 
of beam is provided, the resisting moment of the top 
flange of the beam may include an adjacent part of 
the slab. This tributary part of the slab shall be limited 
as follows: 
To be available the minimum thickness of slab shall 

be one-thirty-second (^) of the slab span. 
The total effective width shall not exceed one-fourth 
(}) of the span length of the beam, or two-fifths (-§-) 
of the slab span, or 8 times the thickness of slab 
plus the thickness of web. 
(c) In T-beams, where the neutral axis falls below the slab, 
the resistance of the web shall be neglected. 

346. Reinforced Columns. Provision must be made in rein- 
forced columns for eccentric loading, if any, and for flexure 
whenever the maximum unsupported length of same exceeds 18 
diams. (Par. 348, c2.) 

[ Proper provisions must also be made at the bottom of the 
columns for tensile stresses, if any, and for the distribution, by 
means of bearing plates or otherwise, of the compressive si resses 
borne by the reinforcement. 

The live loads on columns may be reduced according to 
provisions in Par. 96. 

347. Temperature Stresses. Temperature stresses shall be 
calculated, where the structure cannot expand and contract 
lively, for a variation of not less than 50° F. (Par. 350.) 

Unit Stresses 

348. Normal Concrete and Structural Steel. All parts of 
the reinforced concrete structure shall be so proportioned thai 

the sum of the maximum stresses from all causes shall not exceed 



82 



STANDARD SPECIFICATIONS 



for normal concrete 'Par. 37-5 » reinforced by structural steel 
l Par. 372) the following values in pounds per square inch, except 
as modified in Pars. 349 and 350: 

Axial U 

Concrete none 

Steel, net section 15,1 

Concrete in tension none 

' ' compression, generally (300 II - 

. on bottom side of con- 



(40%) 



tinuous beams near support 700 ' 

Steel in tension 15,1 

compression 9,000 ' 

[Or 15/c, where f e is the allowable stress on the concrete, given 
below under c ]. 

(c) Axial cornp m the concrete: 

1. Columns whose -r^l> diameters. 
a ^ 



1. Columns whose -r <- IS diameters. 



Up to 1: 
Diani. 



From 12-18 
Diam. 



Lbs. 

Plain concrete columns 500 

Columns ^.vith longitudinal reinforcement only . . 500 

. • • reinforcement of bands or hoops. . 600 
longitudinal reinforcement of from 

1-4^ and bands or hoops 750 

Columns reinforced with structural steel shapes 

thoroughly encasing the concrete 750 




20 
20 
25 

32§ 

324- 



2. Columns whose -= > IS diameters 
a 



= 






1 + 



1 . I 






B 



where f c = allowable unit stress, given above for columns of 12 
diamete - 
J= unsupported length of column in inches: 
d= least width, or diameter, of effective area of column in 
inches. Par. 35 



REINFORCED CONCRETE 83 

3. Axial compression, on the steel. 

Rods, shapes, or built-up members, when reinforcing the 

concrete 15/ c 

Shapes or built-up members when independent. 

[See Pars. 12 (c), 65 (c), 117 (c).] 
(d) Shear, on the concrete. 

1. Direct shear only (i.e., shear uncombined with either ten- 

sion or compression) for: 

Beams, having no web reinforcement 40 lbs. (2%) 

■ " , ll bent-up reinforcement 60 lt (3%) 

il , " web reinforcement of bent-up 

bars and stirrups 120 l ' (6< \ ) 

n 01 , . f One-half of compression 

2. shear and compression com- j , . . 

, . r i ' i values given above un- 

billed, equal amount ol each | . - 

[ der (c). 

„ „. , . [ Interpolate between values 

6. bhear and compression com- . . , _ .. 

. . , ,. r ,. \ given under (rf) 1. and 

bined, other ratios ?, x _ 

I (d) 2. 

4. Shear, on the steel (any grade) 10,000 lbs. 

(<?) Diagonal tension, on the concrete 40 ' ' (2%) 

" , on the steel 15,000" (40%) 

(/) Bearing. 

Concrete on concrete (equal areas) .... 500 ' ' (25' , ) 
" " " (less area on 

greater area) 600 " (30%) 
(g) Bond between 

Concrete and plain reinforcing bars . . 80 ' (4%) 

" drawn wire 40 u (2< \ I 

" deformed bars (variable) 100-160" (5-8%) 

349. Other Concretes and Steels. For concretes, differing 

in strength or proportion of aggregates from normal concrete 
(Par. 375), substitute for values given above (Par. 348) their 
ultimate strength in 28 days times percentages as indicated, the 
maximum increase over same being limited to 25 per cent. 

For Steels, differing in strength from structural steel grade 
(Par. 193), substitute for tensile values given above 1 . (Tar. 348) 




STANDARD SPECIFICAT: 3 

:;t of their strength at the yield point, as determined 
by teste 

350. Maximum Stresses. When combining the temperature 
sti se - .th stresses due to all other causes, the specified unit 
si 59es v . 349) may be increased 10 per cent, provided 
that this combination gives a greater sectional area. 

Design j Structure 

351. General Proportions: 

(a) The total thickness of a slab shall not be less" than one- 
thirty-sixth (^) of the slab span in the direction of 
the principal reinforcement, or less than 3 in. 

(6) The minimum width of web, in beams or girders, shall 
not be less than one-twenty-fourth (^) of the span. 
(Par. 342.) 

(c) The maximum diameter of reinforcing rods, in ^ 

beams or girders, shall not exceed one-two-hundredth 

(tto) °f tne span- 

352. Continuous Spans. Where continuity of spans, or 

:e depended upon and allowed for m determining 
the bending moment at center, the slab or beam must be properly 
reinforced over the supports to resist the negative moment. 

353. Bond Strength. Ends of plain reinforcing bars must 
e ured against slipping, either by depending upon the bond, 

in which case the length of the free end shall be not less than 
48 diams. of the rod. or by bending the free end through 
180° to a radius of 4 diams. of rod. or by an anchorage con- 
sisting of the free end being upset and provided with a nut and 
a washer. The free ends of stirrups may. at points where the 
beam has no top reinforcement, be turned closely through 
approximately 360° for this purpose. At points where top 
reinforcement exists the free ends of the stirrups shall pass 
:he same before being so turned, or shall be wound around 
the bars approximately one and one-half (H) turns. 

554. Web Reinforcement. After deducting the shear or 
diagonal tension carried by the concrete (Pa: J48< J48< 
remainder shall be carried by reinforcement consisting of bent 
rods or stirrups, or both. The stirrups shall be properly secured 
against slipping. 'Par. 3" 



REINFORCED CONCRETE 85 

355. Special Reinforcement : 

(a) Rectangular slabs reinforced for strength in one direction 
only shall be reinforced in the other direction, to prevent 
shrinkage cracks, by rods not less than | in. in diameter, 
placed above the main reinforcement and spaced not 
more than 2 ft. c. to c. 

(6) Similar slabs, designed for concentrated loads, shall be 
reinforced perpendicular to the main reinforcement 
by rods -§- in. in diameter, spaced not more than 1 ft. 
c. to c, to distribute such loading. 

(c) Slabs, beams, or girders having construction joints (Par. 

362) shall be provided with shearing rods proportioned 
to transmit shear due to any partial loading. The 
diameter of such shall not be less than -J in., the length 
shall not be less than 96 diameters, the spacing shall not 
exceed 2 ft. c. to c, and they shall be placed near the top. 

(d) Reinforcement against leakage cracks, when water- 

proofing (Par. 360), shall be distributed evenly over 
the entire affected area and shall consist of rods not 
less than J- in. in diameter spaced not over IS in. c. to c. 
in two directions perpendicular to each other, 
(c) Reinforcement for temperature stresses (Par. 347) shall 
be distributed over the entire area of the cross-section 
in a ratio varying with the same. 

356. Splicing of Reinforcement. Wherever it is necessary 
to splice the reinforcement the rods in tension shall be connected 
by a direct splice of a strength equal to that of the rod, or by 
overlapping their ends. The length of lap in diameters shall not 
be less than the total stress in the rod, at point of splice, divided 
by 300. In compression, where reinforcing rods over 1 in. in 
diameter are joined, they shall be butted and fully spliced; rods 
of smaller diameter may be lapped as in tension. 

No splices shall be made at points of maximum stress, 

357. Minimum Reinforcement. The minimum reinforce- 
ment in slabs, beams or girders shall not be less than three- 
fourths of 1 per cent {':[%) of the effective area of the concrete; 
in columns with longitudinal reinforcement only not less than 
2 per cent, and in columns having circumferential reinforcemenl 
such reinforcement shall not be less than 1 percent i>\ the effect- 
ive area. 






86 STANDARD SPECIFICATIONS 

358. Spacing of Reinforcement: 

(a) Slabs The minimum spacing of parallel bars shall not be 
less than 3 in. Two layers of bars perpendicular to 
each other shall be in contact, the bars forming the 
main reinforcement being in all cases placed under- 
most . 

(6) Beams and Girders. The minimum distance from the 
center of any bar to the edge of beam shall be 2 diam- 
eters, or H in. The minimum distance c. to c. of 
any bar in the same layer shall be 2\ diameters for 
round bars and 3 diameters for square bars, and not 
less than 2 diameters between centers of bars in different 
layers. The longitudinal spacing of stirrups or bent 
rods, where used, shall not exceed three-fourths (f) 
of the depth of the beam. 

(r) Columns. In columns having longitudinal reinforcement 
only, the rods shall be securely tied together at inter- 
vals not exceeding 20 diameters of rods. In columns 
having circumferential reinforcement the clear spacing 
of such shall not exceed one-fourth (J) the diameter 
of the inclosed column. 

The circumferential reinforcement shall be securely 
held in position by means of spacing bars, or other 
adequate means. 

359. Fireproofing. The minimum thickness of a fire-retard- 
ing coating, covering the reinforcement, shall be as follows: 

For slabs, not less than \\ diams. of rods, or f inch 
" beams. " H " , or 1J " 

" girders. " H " , or H " 

" columns. " H " , or 1J " 

" columns having no reinforcement, 2 " 

The above coverings shall not be considered as effective area; 
they shall be made of concrete in which no. limestone is used, 
but in which the coarse aggregate may consist of hard-burned 
cinders or other material that will resist high temperatures. 
All aggregates shall be so small that the reinforcement is thor- 
oughly covered, leaving no voids or cracks. ■ 

For further fire-resisting purposes all external angles shall be 
either beveled or rounded. 



REINFORCED CONCRETE 87 

360. Waterproofing. Waterproofing shall be effected by 
using a concrete of maximum density in connection with special 
reinforcement to prevent leakage cracks (Par. 355<i), or by a 
waterproof coating, or by addition of an approved waterproof 
compound. 

The proportion of aggregates to be used in obtaining such 
concrete shall be determined for each case by experiments. 

The waterproof coating shall generally consist of from 4 to 8 
layers of a strong flexible felt or cloth fabric, so treated in manu- 
facture that all pores are closed, cemented together with specially 
prepared preparations of asphalt, coal tar or coal-tar pitch, 
or of a thick layer of a similar bituminous compound applied as 
a mastic, upon the surface after being troweled off with cement 
mortar. (Par. 377.) 

361. Weatherproofing. Concrete may be rendered weather- 
proof, even waterproof under moderate pressure, by applying 
alternate washes of aluminum sulphate and soap, or by a wash 
of cement grout. These washes shall be applied by a soft 
brush after the surface of the concrete has been thoroughly 
cleaned. 

362. Construction Joints. Construction joints in reinforced 
concrete shall, whenever unavoidable, be located as follows: 

In slabs and beams, near the center of the span. 

In girders near the center of the span, except when another 

girder or beam joins at this point. 
In such case the joint shall be offset a distance equal to 

the depth of the girder and shall be reinforced for shear 

if necessary. 
In columns horizontal joints shall preferably be made flush 

with the lower side of the girders, or the upper side of the 

floor line. 
All construction joints in slabs, beams, girders, or columns 

shall be perpendicular to the plane of their surfaces. 

363. Expansion Joints. In exposed work, when no1 fully 
reinforced for temperature stresses, special expansion joints 
shall be provided at intervals usually not exceeding 75 ft. Guides 
for cracks shall be provided at distances to be approved by the 
Engineer. 

Expansion joints shall Interlock, wherever practicable, usu- 
ally by tohgue-and-groove joints in the concrete, reinforced by 



88 STANDARD SPECIFICATIONS 

short steel rods embedded with one end in the concrete, and 
free to slide with the other in embedded gaspipe. 

Materials and Workmanship 

364. Cement. The cement shall be Portland, either American 
or foreign, which will meet the requirements of the standard 
specifications adopted by the American Society for Testing 
Materials. (See Part VIII.) 

365. Fine Aggregates. Fine aggregates are sand and screen- 
ings of either gravel or crushed stone. They shall be graded 
in size up to such grain which, when dry, will pass a screen hav- 
ing |-in. meshes. 

366. Coarse Aggregates. Coarse aggregates most suitable 
for reinforced concrete structures are gravel, broken stone, and 
hard-burned cinders. They shall be screened and of such size 
as will be retained on a screen having -j-in. meshes, but will 
pass a f- or 1-in. mesh, the smaller aggregate being used in 
the fire-ret arcling coating covering the reinforcement. (Par. 
359.) 

367. Sand. The sand shall be clean, coarse, and of grains 
varying in size. It shall not contain clay or loam to the extent 
of more than one-half (i%) per cent and shall be free from any 
other foreign matter. 

368. Gravel. The gravel shall be composed of reasonably 
clean pebbles of hard and durable stones of sizes not exceeding 
f in. in diameter, free from clay and other impurities. To main- 
tain the proper proportions in the concrete mixture it shall be 
screened and divided into fine and coarse aggregate. (Pars. 365, 
366.) 

369. Stone. The stone shall be clean, sound, hard, durable, 
and free from all foreign matters, crushed or broken to sizes 
not exceeding 1 in. in diameter. Only such stones as will break 
in approximately cubical pieces shall be used; those, like slate 
or shale, which break in thin flat pieces, shall be rejected. To 
maintain the proper proportions in the concrete mixture it 
shall be screened and divided into fine and coarse aggregate. 
(Pars. 365, 366.) 

370. Cinders. Hard-burned cinders may be used as the coarse 
aggregate of a fire-resisting coating. (Par. 359.) They shall be 



REINFORCED CONCRETE 89 

composed of hard, clean, vitreous clinker, free from sulphides, 
unburned coal, or ashes. 

371. Water. The water shall be clean, free from oils, acids, 
strong alkalies, or vegetable matter. 

372. Metal Reinforcement. The reinforcement shall pref- 
erably consist of structural steel conforming to the specifica- 
tions adopted by the Association of American Steel Manufacturers, 
1910. (See Part V, Pars. 192 to 201.) 

In general round bars are preferable to square bars. Deformed 
bars of hard steel and cold-twisted bars may be used in special 
cases. 

For the prevention of shrinkage cracks, leakage cracks, and as 
reinforcement for temperature stresses, or for minor details, 
the bars used need not be tested. All other bars shall be 
tested. 

373. Proportions. The proportion of the materials in the 
concrete and the percentage of the reinforcement shall be specif- 
ically stated in the contract. 

The aggregates used in the concrete shall be carefully selected, 
of uniform quality and proportioned so as to secure as nearly 
as possible a maximum density. 

In ordinary work the proportions may be selected according 
to judgment based upon experience; but in important work, 
or where waterproofing is required, the correct proportions for 
maximum density shall be determined in each case by experiments. 

374. Unit of Measure. The unit of measure shall be the 
barrel, which shall be taken as containing 3.8 cu. ft. and shall 
contain 376 lb. of cement net. A bag of cement shall contain 
94 lb. of cement net. 

375. Normal Concrete. For reinforced concrete work " nor- 
mal concrete " shall be composed of 1 pari Portland cement and 
6 parts of aggregate, approximately 2 parts of tine and approx- 
imately 4 parts of coarse aggregates, which shall he measured 
separately capable of developing an average compressive 
strength of 2000 lb. per sq.in. in 28 days, when tested in cylin- 
ders S in. in diameter and 10 in. Long, under laboratory con 
ditions of manufacture and storage, using the same consistency 
as is used in the held. 

376. Other Concretes. The strength ami suitability of 
concretes, other than normal concrete, tor reinforced concrete 



STANDARD SPECIFICATH >XS 

work will depend upon the richness or the leanness of the mixture 
and the character of the agg: _ 

The structural value of such concretes shall be based upon 
the average con. - -trength in 2 v y& as determined al 
for nonnal concrete. P 

377. Cement Mortar. Cement mortar, used in reinforced 
concrete work, shall generally be composed of 1 pan Portland 

oent and from 2 to 3 rts of fine aggregates. The mortar 
shall be mixed by hand. (Par. 33C 

378. Cement Grout. Cement grout, used in reinforced 
concrete work, shall be composed of neat Portland cement mixed 
with water to a consistency of thick cream or whitewash. 

379. Workmanship: 

All material ana shall be of the best quality in every 

respect and shall be subject to inspection and approval 
any time during the progress of the work. 

(b) The entire work shall be constructed in a substantial 

and workmanlike manner, and to the satisfaction and 
acceptance of the Engineer. (Par. 383. 

(c) The contractor shall employ skilled or suitable mechanics 

and laborers for every kind of work and shall, at the 
request of the Engineer, discharge any workman whom 
he deems incompetent, negligent, or untrustworthy. 

380. Facing. See Par. 318 

381. Finishing: 

(a) The finishing of the surface shall be determined before 
the concrete is placed and the work conducted - 
to make possible the finish desired. 

(6) After the fomis are removed any small cavities or open- 
ings in the face shall be neatly filled with cement mortar, 
if necessary in the opinion of the Engineer. Any 
ridges due to cracks or joints in the lumber shall be 
nibbed down with chisel or wooden fk 
When desired the face may be covered with a finish 
thin grout, or a whitewash, applied with a brush. 
Plastering shall not be applied to any face exposed to 
the weather. 
Before the concrete has thoroughly set the face may be 
treated with a wire brush; after having hardened with 
~ :»ft brick, with hand or pneumatic tools. 




REINFORCED CONCRETE 91 

(e) A colored finish may be obtained by using naturally 
colored aggregates, or by adding a mineral pigment of 
any desired shade when mixing the concrete, as may 
be determined by the Engineer. 

Inspection and • Erection 

382. Inspection. Inspection during construction shall be 
made by competent inspectors employed by, and under the 
supervision of, the Engineer, and shall cover the following: 

(a) The materials. 

(b) The correct construction and erection of the forms and 

the supports. 

(c) The sizes, shapes, and arrangement of the reinforcement. 

(d) The proportioning, mixing, and placing of the concrete. 

(e) The strength of the concrete by tests upon standard test 

pieces made on the work. 
(/) The protection of the work against frost, the sun and the 

weather generally. 
(g) Whether the concrete is sufficiently hardened before the 

forms and supports are removed. 
(h) Prevention of injury to airy part of the structure by and 

after the removal of the forms and shores. 
(i) Comparison of dimensions of all parts of the finished 

structure with the plans. 

383. Accepting Material or Work. If the inspector, through 
an oversight or otherwise, has accepted material or work which 
is defective or contrary to the specifications, the material or 
work, no matter in what stage of completion, may be rejected 
by the Engineer. 

384. Testing the Structure. Load test on any part o\ the 
finished structure shall be made where, in the opinion of the 
Engineer, there is a reasonable suspicion that the work lias not, 
been properly performed, or that, through influences of some 
kind, the strength has been impaired, and may he made in any 
case. 

The test load applied shall not exceed that which will cause 

a total stress in the reinforcement of three-fourths (}) o( ds 

Strength at the yield ] oint , or more than twice the superimposed 
load. 



92 



STANDARD SPECIFICATIONS 



The test load shall be left on the part under test for 24 hours, 
shall not cause a deflection exceeding one-four-hundred-and- 
eightieth (4 so) of the span,, shall show no sign of cracks, and 
shall leave no permanent deformation. 

Load tests shall not be made upon arches until after 90 days, 
or upon other structures until after 60 days, of hardening. 

385. Erection: 

(a) Whenever the contractor is required to remove any 
existing structure, to clear the site, or to excavate, such 
requirements shall be specifically stated in the con- 
tract. 

(6) Otherwise the erection shall include all necessary* hauling, 
the unloading of the materials and their proper care 
until the completion and acceptance of the work, as 
specified in Pars. 385c to 391. 

(c) The contractor shall furnish, at his own expense, . all 
necessaiy staging, falsework, materials, and tools, and 
shall erect the structure complete and finish the same 
as specified in the contract. (Par. 390.) 

386. Removal of Old Structure. Whenever new structures 
are to replace existing ones the latter shall be carefully taken 
down and removed by the contractor to some place specified 
in the contract. 

387. Interruption of Traffic. All operations shall be so con- 
ducted as not to impede or interrupt the work of other contrac- 
tors, the traffic of any railroad, nor close any thoroughfare or 
waterway, nor conflict with any law, regulation, or ordinance 
of any properly constituted authority. 

388. Permits. Before commencing operations the contrac- 
tor shall, at his own expense, obtain all necessary permits and 
comply with their requirements. 

389. Safeguards and Damages. The contractor shall furnish, 
at his own expense, all watchmen, guards, signals, night lights, 
etc., for the prevention of accidents, and be responsible for the 
safety of the structure; and he shall assume full responsibility 
for all accidents to men, animals ; and materials before the com- 
pletion and final acceptance of the structure and shall indemnify 
its owner for any and all claims for damages arising there- 
from. 

390. Defective Work. The contractor shall, at his own 



REINFORCED CONCRETE 93 

expense, remove, rebuild, or make good any damaged material 
or defective work, even if same through an oversight or other- 
wise has been previously accepted. 

391. Clearing up. When the erection is completed the con- 
tractor shall, at his own expense, remove all falsework, rubbish, 
and other useless material caused by his operations. 



INDEX 



REFERENCES ARE TO PARAGRAPHS, NOT PAGES 



Accepting materials or work, 244, 
383 
access to mills, 240 
" " shops, 243 
aggregates, coarse, 366 

, fine, 365 
allowable variation, 177 

in weight, 188, 
189 
all structures, 86, 133 
alternate stresses, 122 
analysis, chemical, 181 
anchor bolts, 46 
annealed specimens, 183 
annealing, 232 

approaches for highway bridges, !JS 
assembling, 220 

"Dases for columns, 45, 101 
- L ' beam girders, 28 
bearing power of piles, 21 
bearings for bridges, 151, 231 
" girders, 151, 173 
bending tests, 179 
bends, nicked, 180 
bond strength, 353 
bolts, anchor, 46, 148 

" , turned, 218 
bracing, 25, 83, 131, 168 
bridges, beam-, 79, 125, 127 

" , deck, 81/ 129 

" , pony, 80, 128 

" , skew, 158 

" , through, 82, 130, 157 
, type of, 50 
buns, 213 

CAMBER, 103, 150 
cast iron, 17, L90 
cast steel, 70, 233 
ceiling, 272 
cement, 288 306, 364 



I cement, constancy of volume, 293, 
299, 305 
' ' , definition of, 295, 300 
' ' , fineness of, 290, 296, 302 
' ' , for concrete, 307 
" , general conditions, 294 
' ' , grout, 378 
' ' , magnesia in, 306 
' ' , mortar, 377 
' ' , natural, 295-299 
' ' , Portland, 300-306 
" , specific gravity of, 289, 301 
" , sulphuric acid in, 306 
" , time of setting, 291, 297, 

303 
' ' , tensile strength of, 292, 298, 
304 
centrifugal force, 63, 116 
chemical analysis, 181, 194 
cinders, 370 

classification of highway bridges, 40 
cleaning, 249 

clearances, in bridges, 52, 106 
clearing up, 263, 391 
columns, 9, 41. 346 
column bases, 15, 101 
combined stresses, 11.71, 121 
compression flange, L63 

members, 39, 96, 1 13 
concrete, normal, 375 
" , other. 376 
" , placing of, 333 

condition of surfaces, 252 

connection angles, 209 

, details of 32, 89, L36 
, field, 208 
contact surfaces, 250 

copies of mill orders, _ >: >s 
counter si resses, 123 
covering, roof, "> 

crane loads,' 10 

cross i ies, 283 



96 INDEX 

REFERENCES ARE TO PARAGRAPHS, NOT PAGES 

Damages, safeguards and, 261, 389 
dead loads, 1, 2, 3, 4, 5, 59 
109, 154, 336 



deck bridges, 81, 129 
defective material, 187 

work, 262, 390 
depositing concrete, 316 
design of flanges, 160 

" plate girders, 159 
" " web, 165 
details of connections, 32, 89, 
" joints, 31, 88, 135 



136 



T^ccentric stresses, 15, 72 

-*-^ edge distance of rivets, 35, 140, 

172 
edge planing, 206 

elongation, modification in, 178, 198 
erection, 256-264, 385 

' ' by purchaser, 264 
expansion joints in concrete, 317, 
363 
rollers, 13, 48, 69 
eye-bars, 37, 94, 142, 224, 225 
eye-bar tests, 248 

THacilities for mill inspection, 239 
-*• facilities for shop inspection, 

241 
facing concrete, 318, 380 
field connections, 208 

" rivets, 217 
fillers, 220 
finish, 185, 205, 207 
finishing concrete, 320, 381 
fireproofing, 359 
flanges, compression, 163 
' ' , design of, 160 
" , plates, 161 
' ' , rivets, 164 
' ' , splices, 162 
floor framing, 77, 126 
flooring, timber, 271, 278, 279 
floors, live loads on, 9 
1 ' , paved, 53 

" , wooden, 271, 279, 280, 281 
force, centrifugal, 63, 116 
" , lateral, 113 
" , traction, 64, 115 
form of specimens, 182, 196 
forms for concrete, 315, 326, 335 
foundation, pressure on, 19, 66, 118 
reezing weather, 322, 334, 335 



/Girder, beam, 28 

^ girder, design of, 159 

girder, plate, 153, 174 

girts, 27 

general dimensions, 342 

" proportions, 76, 125, 156 

" requirements, 49-58, 105— 

108, 153 
" workmanship. 202 

gravel, 310, 368 

grout, 378 

guard rails, 284 
' ' , wheel, 281 

TJand railing for bridges, 57, 282 
*■■*- heavier loading, 111 

Tn accessible surfaces, 251 
-*■ ingredients in concrete, 329 
inspection, 238-248, 382 
interruption of traffic, 258, 387 
impact, 11, 61, 112, 341 
iron, cast, 17, 190 
" , wrought, 191 



Joints, details of, 31, 88, 135 

^ joints, expansion in concrete, 



317, 363 
joints, finish of, 207 



oists, timber, 278, 280 



Lateral forces, 113 
lattice-bars, 42, 145, 204 
load, crane, 10 
" , dead, 1, 2, 3, 4, 5, 59, 109, 154, 

336 
" , live, 9, 60, 110, 111, 340 
" , snow, 6 

TV/TACHiNE-finished surfaces, 253 
-L"- manufacture, process of, 175, 

192 
material for buildings, 3, 4, 5 
" bridges, 51, 105 
" ' ' concrete reinforcing bars, 

192-201 
" " rivet steel, 175-189 
" " structural steel, 175-189 
" , defective, 187 
maximum stresses, 73, 350 
mill, access to, 240 
' ' inspection, facilities for, 239 



INDEX 

REFERENCES ARE TO PARAGRAPHS 

mill orders, copies of, 238 
minimum size of material, 30, 87, 134, 

169 
mixing concrete, 312, 313 
modification in elongation, 178, 198 
mortar, cement, 377 



97 



NOT PAGES 



Natural cement, constancy of 
volume, 299 
natural cement, definition, 295 
" ' ' , fineness, 296 

' ' , tensile strength, 298 

' ' , time of setting, 297 
nicked bends, 180 
number of tests, 184, 197 
" twists, 199 

T)ainting, 249-255 

-*- ' ' , after erection, 255 

, omitted, 254 
paved floors, 53 
permits, 259, 388 
pin holes, 44, 147, 226, 227 
pins, 43, 146, 228 
piles, bearing power on, 21 
' ' , specification for, 270 
' ' , trestles, 285 
' ' , unit stresses for, 277 
pilot nuts, 229 
pitch of roofs, 24 
planks, 273 
pony bridges, 80, 128 
Portland cement: 

constancy of volume, 305 

definition, 300 

fineness, 302 

magnesium in, 306 

specific gravity, 301 

sulphuric acid in, 306 

tensile strength, 304 

time of setting, 303 
Portland-cement concrete: 

cement for, 307 

consistency, 314 

depositing, 316 

expansion joints in, 317 

facing, 318 

finishing of, 320 

forms for, 315 

freezing weather, 322 
gravel for, 310 
mixing by hand, 312 
" " machine, 313 



Portland-cement, proportions of, 319 
sand for, 308 
stone for, 309 
water for, 311 
waterproofing of, 321 
pressures, on foundations, 19, 66, 118 
" , on soils, 20 
" , on walls, 18 
process of manufacture, 175, 192 
proportions, general, 76, 125, 156 
of concrete, 319, 351 
punching, 211, 212 

DEAMING, 212, 214 

■*-* Reinforced concrete: 

accepting material, 383 

work, 383 
adherence to plans, 325 
aggregate, coarse, 366 

, fine, 365 
assumptions, 343 
bending moments, 344 
bond strength, 353 
cement for, 364 

" -grout, 378 

" -mortar, 377 
centrifugal force, 338 
cinders, 370 
clearing up, 391 
columns, 346 
construction joints, 362 
continuous spans, 352 
damage, 389 
dead load, 336 
defective work, 390 
erection, 385 
expansion joints, 363 
facing. 380 
finishing, 381 
fireproofing of, 359 
freezing weather, 33 1 
general dimensions, 342 
proportions, 351 
gravel, 368 
impact, 3 1 1 
ingredients for, 329 
inspection, 382 
interruption of t raflfic, 387 
live loads. 340 
maximum st resses, 350 
minimum reinforcement . '^'■>7 
metal reinforcement, 327. 372 
mixing bj hand, 312, 330 



98 



INDEX 



REFERENCES ARE TO P 

reinforced concrete, maxing by ma- 
chine, 313. 331 
normal concrete, 348, 375 
other concretes, 349, 376 

' ' steels, 349 
permits, 388 
placing of concrete, 333 
" forms, 326 
" reinforcement, 328 
preparations of plans, 324 
proportions, 373 
removal of forms, 335 

" "old structures, 386 
resisting moments, 345 
safeguards, 389 
sand for, 367 

spacing of reinforcement, 358 
special reinforcement, 355 
splicing of reinforcement, 356 
stone for, 369 
temperature stresses, 347 
testing the structure, 384 
traction force, 339 
unit of measure, 374 
unit stresses, 348 
water for. 372 
waterproofing of, 360 
web reinforcement, 355 
weatherproofmg of, 361 
wind pressure, 337 
workmanship, 379 
removal of old structures. 257, 386 
requirements, schedule of, 176, 193 
reversal of stresses. 16, 74 
riveted work. 90, 137 
rivet holes, 210 
riveting, 219 
rivets, 33, 87, 138, 170 

, edge distance of. 35, 140 

, field, 217 

, how driven, 216 

in flanges, 164 
, size of, 215 

, spacing of, 34, 139, 171 
rods, 38, 95 

rollers, expansion, 13. 48, 69, 228 
roof, bracing of, 25 
" covering, 3 
" , design of, 22 
1 ' load, 8 
' ' , pitch of, 24 
roof trusses, spacing of, 23 
" , weight of, 5 



ARAGRAPHS, NOT PAGES 

Qafeguards and damages. 261 

^ 389 

sand, 308, 367 

scantling, 273 

schedule of requirements, 176, 193 

screw threads, 230 

shingles, 269 

shipping details, 235 

" invoices, 246 
shop inspection, facilities for. 241 

' ' plans, 245 
shops, access to, 243 

" , starting work in. 242 
skew-plate girder bridges, 158 
snow load, 6 
soil, pressure on, 20 
spacing of rivets, 34, 139 
specimen, annealed, 183 

, form of, 182. 196 
splices in flanges, 162 
" " plates, 222 
" " web, 166 
stamping, 186 
steel, cast, 70, 233 
" , cold-twisted, 193 
' ' , hard- grade, 193 
" , structural. 175-189 

-grade, 193 
" , trestles, 84, 132 
stiffeners, web, 167 
stone, 309, 369 
straightening material, 203 
stresses, alternate, 122 

" ., combined, 14, 71. 124 
" , counter, 123 
" , eccentric. 15. 72 
11 , maximum. 73 
" , reversal of, 16. 74 
stringers, in trestles, 287 
structures, all, 86, 133 
sub-punching, 212 
surfaces, condition of. 252. 
" , inaccessible, 251 
" , machine-finished, 253 

TEMPERATURE, 47, 104, 152, 174. 
347 
tension members, 36, 93, 141 
testing the structure, 384 
tests, bending, 179 
" , eve-bars. 248 
' ' , number of, 184, 197 
" , to prove workmanship, 247 



INDEX 



99 



REFERENCES ARE TO PARAGRAPHS, NOT PAGES 



tie-plates, 40, 144 

ties, cross, 283 

through bridges, 80, 130, 157 

timber, dimension, 274 

, dressing of sawed, 268 
, flooring, 271, 278, 279 
, joists, 278, 280 
, kinds of, 265 
, quality of, 266 
, size of sawed, 267 
, unit stresses in, 275, 276 
traction forces, 64, 115, 339 
traffic, interruption of, 258 
trestles, column bases for, 101 . 
' ' , pile, 285 
" , steel, 84, 132 
" , wooden, 285, 286, 287 
trusses, roof, design of, 22 
" , " , spacing of, 23 
• ' , weight of, 5 
turned bolts,, 218 
type of bridge, 50 
twists, number of, 199 



U 



nit stresses: 

in bridges, 65, 117, 155 

in buildings, 12 

in cast iron, 17 

in cast steel, 70 

in piles, 21, 277 

in reinforced concrete, 348, 

349, 350 
in timber, 275, 276 



TTariations, allowable, 177 

* variations, in pin holes, 227 
variations, in weight, 188, 189, 
201 



TTTall plates, 45 • 

"* wall plates, pressure on, 18 
wainscoting, 272 
water, 311, 372 
waterproofing, 321, 361 
weatherproofing, 362 
web, design of, 165 

' ' , plates, 221 

" , reinforced, 354 

' ' , splices, 166 

" , stiff eners, 167, 223 
weight, 236, 237 
welds, 234 
wheel guards, 281 

wind pressure, on bridges, 62, 
114 
" , on buildings, 7 
wooden floors, 271, 279, 280 281 

trestles, 285, 286, 287 
work, defective, 262 

" , riveted, 90, 137 
workmanship, 202-248, 379 
wrought- iron bars, 191 



'ield point, 176, 195 



OCT 1 1910 



One copy del. to Cat. Div. 
0C1 1/ 7I*1C 



